Item 8. Financial Statements and Supplementary Data

Report of Independent Registered Public Accounting Firm

To the Shareholders and the Board of Directors of Aon plc

Opinion on the Financial Statements

We have audited the accompanying consolidated statements of financial position of Aon plc (the Company) as of December 31, 2023 and 2022, the related consolidated statements of income, comprehensive income, shareholders’ equity (deficit) and cash flows for each of the three years in the period ended December 31, 2023, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2023, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), and our report dated February 16, 2024, expressed an unqualified opinion thereon.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the account or disclosure to which it relates.

			Realizability of Deferred Tax Assets
Description of the Matter			As discussed in Note 10 “Income Taxes” of the Notes to Consolidated Financial Statements, the Company had net deferred tax assets of $1,080 million at December 31, 2023. Deferred tax assets are reduced by a valuation allowance if, based on the weight of all available evidence, in management’s judgment it is more likely than not that some portion, or all, of the deferred tax assets will not be realized. Conclusions on the realizability of certain net deferred tax assets involve significant management judgement including assumptions and estimates related to the amount, timing, and jurisdiction of future taxable income. Auditing the net deferred tax asset calculation and the related projection of future taxable income was especially challenging as it involved a high degree of auditor judgement around management’s assumptions and estimates of future taxable income.
How We Addressed the Matter in Our Audit			We obtained an understanding, evaluated the design and operating effectiveness of internal controls that address the risks of material misstatement relating to the realizability of deferred tax assets, including controls over management’s projections of the amount, timing, and jurisdiction of future taxable income. Among other audit procedures performed, we evaluated the assumptions used by the Company to develop projections of future taxable income by income tax jurisdiction and tested the completeness and accuracy of the underlying data used in the projections. We compared the projections of future taxable income with the actual results of prior periods. Further, we involved tax subject matter professionals in the review of the information identified.

We have served as the Company’s auditor since 1986.

Chicago, Illinois

February 16, 2024

Aon plc

Consolidated Statements of Income

						Years Ended December 31
(millions, except per share data)						2023						2022						2021
Revenue
Total revenue						$	13,376					$	12,479					$	12,193
Expenses
Compensation and benefits						6,902						6,477						6,738
Information technology						534						509						477
Premises						294						289						327
Depreciation of fixed assets						167						151						179
Amortization and impairment of intangible assets						89						113						147
Other general expense						1,470						1,271						2,235
Accelerating Aon United Program expenses						135						—						—
Total operating expenses						9,591						8,810						10,103
Operating income						3,785						3,669						2,090
Interest income						31						18						11
Interest expense						(484)						(406)						(322)
Other income (expense)						(163)						(125)						152
Income before income taxes						3,169						3,156						1,931
Income tax expense						541						510						623
Net income						2,628						2,646						1,308
Less: Net income attributable to noncontrolling interests						64						57						53
Net income attributable to Aon shareholders						$	2,564					$	2,589					$	1,255
Basic net income per share attributable to Aon shareholders						$	12.60					$	12.23					$	5.59
Diluted net income per share attributable to Aon shareholders						$	12.51					$	12.14					$	5.55
Weighted average ordinary shares outstanding - basic						203.5						211.7						224.7
Weighted average ordinary shares outstanding - diluted						205.0						213.2						226.1

See accompanying Notes to Consolidated Financial Statements.

Aon plc

Consolidated Statements of Comprehensive Income

						Years Ended December 31
(millions)						2023						2022						2021
Net income						$	2,628					$	2,646					$	1,308
Less: Net income attributable to noncontrolling interests						64						57						53
Net income attributable to Aon shareholders						2,564						2,589						1,255
Other comprehensive income (loss), net of tax:
Change in fair value of financial instruments						13						(13)						1
Foreign currency translation adjustments						276						(528)						(289)
Postretirement benefit obligation						(40)						(211)						277
Total other comprehensive income (loss)						249						(752)						(11)
Less: Other comprehensive loss attributable to noncontrolling interests						(1)						—						(1)
Total other comprehensive income (loss) attributable to Aon shareholders						250						(752)						(10)
Comprehensive income attributable to Aon shareholders						$	2,814					$	1,837					$	1,245

See accompanying Notes to Consolidated Financial Statements.

Aon plc

Consolidated Statements of Financial Position

						As of December 31
(millions, except nominal value)						2023						2022
Assets
Current assets
Cash and cash equivalents						$	778					$	690
Short-term investments						369						452
Receivables, net						3,254						3,035
Fiduciary assets						16,307						15,900
Other current assets						996						646
Total current assets						21,704						20,723
Goodwill						8,414						8,292
Intangible assets, net						234						447
Fixed assets, net						638						558
Operating lease right-of-use assets						650						699
Deferred tax assets						1,195						824
Prepaid pension						618						652
Other non-current assets						506						509
Total assets						$	33,959					$	32,704
Liabilities and equity (deficit)
Liabilities
Current liabilities
Accounts payable and accrued liabilities						$	2,262					$	2,114
Short-term debt and current portion of long-term debt						1,204						945
Fiduciary liabilities						16,307						15,900
Other current liabilities						1,878						1,347
Total current liabilities						21,651						20,306
Long-term debt						9,995						9,825
Non-current operating lease liabilities						641						693
Deferred tax liabilities						115						99
Pension, other postretirement, and postemployment liabilities						1,225						1,186
Other non-current liabilities						1,074						1,024
Total liabilities						34,701						33,133
Equity (deficit)
Ordinary shares - $0.01 nominal value Authorized: 500.0 shares (issued: 2023 - 198.6; 2022 - 205.4)						2						2
Additional paid-in capital						6,944						6,864
Accumulated deficit						(3,399)						(2,772)
Accumulated other comprehensive loss						(4,373)						(4,623)
Total Aon shareholders' deficit						(826)						(529)
Noncontrolling interests						84						100
Total deficit						(742)						(429)
Total liabilities and equity (deficit)						$	33,959					$	32,704

See accompanying Notes to Consolidated Financial Statements.

Aon plc

Consolidated Statements of Shareholders’ Equity (Deficit)

(millions, except per share data)						Shares						Ordinary Shares and Additional Paid-in Capital						Retained Earnings (Accumulated Deficit)						Accumulated Other Comprehensive Loss, Net of Tax						Non-controlling Interests						Total
Balance at January 1, 2021						225.5						6,314						1,042						(3,861)						88						3,583
Net income						—						—						1,255						—						53						1,308
Shares issued — employee stock compensation plans						1.7						(129)						(1)						—						—						(130)
Shares repurchased						(12.4)						—						(3,543)						—						—						(3,543)
Share-based compensation expense						—						449						—						—						—						449
Dividends to shareholders ($1.99 per share)						—						—						(447)						—						—						(447)
Net change in fair value of financial instruments						—						—						—						1						—						1
Net foreign currency translation adjustments						—						—						—						(288)						(1)						(289)
Net postretirement benefit obligation						—						—						—						277						—						277
Net purchases of shares from noncontrolling interests						—						(8)						—						—						(5)						(13)
Dividends paid to noncontrolling interests on subsidiary common stock						—						—						—						—						(38)						(38)
Balance at December 31, 2021						214.8						6,626						(1,694)						(3,871)						97						1,158
Net income						—						—						2,589						—						57						2,646
Shares issued — employee stock compensation plans						1.7						(156)						(1)						—						—						(157)
Shares repurchased						(11.1)						—						(3,203)						—						—						(3,203)
Share-based compensation expense						—						397						—						—						—						397
Dividends to shareholders ($2.19 per share)						—						—						(463)						—						—						(463)
Net change in fair value of financial instruments						—						—						—						(13)						—						(13)
Net foreign currency translation adjustments						—						—						—						(528)						—						(528)
Net postretirement benefit obligation						—						—						—						(211)						—						(211)
Net purchases of shares from noncontrolling interests						—						(1)						—						—						(1)						(2)
Dividends paid to noncontrolling interests on subsidiary common stock						—						—						—						—						(53)						(53)
Balance at December 31, 2022						205.4						6,866						(2,772)						(4,623)						100						(429)
Net income						—						—						2,564						—						64						2,628
Shares issued — employee stock compensation plans						1.6						(168)						(1)						—						—						(169)
Shares repurchased						(8.4)						—						(2,700)						—						—						(2,700)
Share-based compensation expense						—						438						—						—						—						438
Dividends to shareholders ($2.41 per share)						—						—						(490)						—						—						(490)
Net change in fair value of financial instruments						—						—						—						13						—						13
Net foreign currency translation adjustments						—						—						—						277						(1)						276
Net postretirement benefit obligation						—						—						—						(40)						—						(40)
Net purchases of shares from noncontrolling interests						—						(190)						—						—						(23)						(213)
Dividends paid to noncontrolling interests on subsidiary common stock						—						—						—						—						(56)						(56)
Balance at December 31, 2023						198.6						$	6,946					$	(3,399)					$	(4,373)					$	84					$	(742)

See accompanying Notes to Consolidated Financial Statements.

Aon plc

Consolidated Statements of Cash Flows

						Years Ended December 31
(millions)						2023						2022						2021
Cash flows from operating activities
Net income						$	2,628					$	2,646					$	1,308
Adjustments to reconcile net income to cash provided by operating activities:
Gain from sales of businesses						(4)						(54)						(142)
Depreciation of fixed assets						167						151						179
Amortization and impairment of intangible assets						89						113						147
Share-based compensation expense						438						397						449
Deferred income taxes						(373)						(252)						11
Other, net						28						170						5
Change in assets and liabilities:
Receivables, net						(188)						(96)						(119)
Accounts payable and accrued liabilities						13						(22)						264
Accelerating Aon United Program liabilities						99						—						—
Current income taxes						174						216						200
Pension, other postretirement and postemployment liabilities						8						(53)						(124)
Other assets and liabilities						356						3						4
Cash provided by operating activities						3,435						3,219						2,182
Cash flows from investing activities
Proceeds from investments						76						110						58
Purchases for investments						(67)						(107)						(91)
Net sales (purchases) of short-term investments - non fiduciary						85						(175)						15
Acquisition of businesses, net of cash and funds held on behalf of clients						(35)						(162)						(14)
Sale of businesses, net of cash and funds held on behalf of clients						5						81						218
Capital expenditures						(252)						(196)						(137)
Cash provided by (used for) investing activities						(188)						(449)						49
Cash flows from financing activities
Share repurchase						(2,700)						(3,203)						(3,543)
Proceeds from issuance of shares						72						58						55
Cash paid for employee taxes on withholding shares						(241)						(215)						(185)
Commercial paper issuances, net of repayments						(27)						(65)						671
Issuance of debt						744						1,967						1,495
Repayment of debt						(350)						(500)						(413)
Increase in fiduciary liabilities, net of fiduciary receivables						358						702						568
Cash dividends to shareholders						(489)						(463)						(447)
Noncontrolling interests and other financing activities						(232)						(71)						(125)
Cash used for financing activities						(2,865)						(1,790)						(1,924)
Effect of exchange rates on cash and cash equivalents and funds held on behalf of clients						264						(549)						(235)
Net increase in cash and cash equivalents and funds held on behalf of clients						646						431						72
Cash and cash equivalents and funds held on behalf of clients at beginning of year						7,076						6,645						6,573
Cash and cash equivalents and funds held on behalf of clients at end of year						$	7,722					$	7,076					$	6,645
Reconciliation of cash and cash equivalents and funds held on behalf of clients:
Cash and cash equivalents						$	778					$	690					$	544
Cash and cash equivalents and funds held on behalf of clients classified as held for sale						43						—						—
Funds held on behalf of clients						6,901						6,386						6,101
Total cash and cash equivalents and funds held on behalf of clients						$	7,722					$	7,076					$	6,645
Supplemental disclosures:
Interest paid						$	446					$	351					$	328
Income taxes paid, net of refunds						$	740					$	546					$	412

See accompanying Notes to Consolidated Financial Statements.

Notes to Consolidated Financial Statements

1. Basis of Presentation

The accompanying Consolidated Financial Statements and Notes thereto have been prepared in accordance with U.S. GAAP. The Consolidated Financial Statements include the accounts of Aon plc and all of its controlled subsidiaries (“Aon” or the “Company”). Intercompany accounts and transactions have been eliminated. The Consolidated Financial Statements include, in the opinion of management, all adjustments (consisting of normal recurring adjustments and reclassifications) necessary to present fairly the Company’s consolidated financial position, results of operations, and cash flows for all periods presented.

Use of Estimates

The preparation of the accompanying Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of reserves and expenses. These estimates and assumptions are based on management’s best estimates and judgments. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment. Management believes its estimates to be reasonable given the current facts available. Aon adjusts such estimates and assumptions when facts and circumstances dictate. Illiquid credit markets, volatile equity markets, and foreign currency exchange rate movements increase the uncertainty inherent in such estimates and assumptions. As future events and their effects cannot be determined with precision, actual results could differ significantly from these estimates. Changes in estimates resulting from continuing changes in the economic environment would, if applicable, be reflected in the Consolidated Financial Statements in future periods.

2. Summary of Significant Accounting Principles and Practices

Revenue Recognition

The Company generates revenues primarily through commissions, compensation from insurance and reinsurance companies for services provided to them, and fees from customers. Commissions and fees for brokerage services vary depending upon several factors, which may include the amount of premium, the type of insurance or reinsurance coverage provided, the particular services provided to a client, insurer, or reinsurer, and the capacity in which the Company acts. Compensation from insurance and reinsurance companies includes: (1) fees for consulting and analytics services and (2) fees and commissions for administrative and other services provided to or on behalf of insurers. In Aon’s capacity as an insurance and reinsurance broker, the service promised to the customer is placement of an effective insurance or reinsurance policy, respectively. The customer obtains control over the services promised by the Company at the completion of the insurance or reinsurance policy placement process once coverage is effective. Judgment is not typically required when assessing whether the coverage is effective. Fees from clients for advice and consulting services are dependent on the extent and value of the services provided. Payment terms for the Company’s principal service lines are discussed below; the Company believes these terms are consistent with current industry practices. Significant financing components are typically not present in Aon’s arrangements.

The Company recognizes revenue when control of the promised services is transferred to the customer in the amount that best reflects the consideration to which the Company expects to be entitled in exchange for those services. For arrangements where control is transferred over time, an input or output method is applied that represents a faithful depiction of the progress towards completion of the performance obligation. For arrangements that include variable consideration, the Company assesses whether any amounts should be constrained. For arrangements that include multiple performance obligations, the Company allocates consideration based on their relative fair values.

Costs incurred by the Company in obtaining a contract are capitalized and amortized on a systematic basis that is consistent with the transfer of control of the services to which the asset relates, considering anticipated renewals when applicable. Certain contract related costs, including pre-placement brokerage costs, are capitalized as a cost to fulfill and are amortized on a systematic basis consistent with the transfer of control of the services to which the asset relates, which is generally less than one year.

The Company has elected to apply practical expedients to not disclose the revenue related to unsatisfied performance obligations if (1) the contract has an original duration of 1 year or less, (2) the Company has recognized revenue for the amount in which it has the right to bill, and (3) the variable consideration is allocated entirely to an unsatisfied performance obligation which is recognized as a series of distinct goods or services that form a single performance obligation.

Disaggregation of Revenue

The following is a description of principal service lines from which the Company generates its revenue:

Commercial Risk Solutions includes retail brokerage, specialty solutions, global risk consulting and captives management, and Affinity programs. Revenue primarily includes insurance commissions and fees for services rendered. Revenue is predominantly recognized at a point in time upon the effective date of the underlying policy (or policies), or for a limited number of arrangements, over the term of the arrangement using output measures to depict the transfer of control of the services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those services. For arrangements recognized over time, various output measures, including units delivered and time elapsed, are utilized to provide a faithful depiction of the progress towards completion of the performance obligation. Revenue is recorded net of allowances for estimated policy cancellations, which are determined based on an evaluation of historical and current cancellation data. Reimbursements received for out-of-pocket expenses are generally recorded as a component of revenue. Commissions and fees for brokerage services may be invoiced near the effective date of the underlying policy or over the term of the arrangement in installments during the policy period.

Reinsurance Solutions includes treaty reinsurance, facultative reinsurance, Strategy and Technology Group, and capital markets. Revenue primarily includes reinsurance commissions and fees for services rendered. Revenue is predominantly recognized at a point in time upon the effective date of the underlying policy (or policies), or for a limited number of arrangements, over the term of the arrangement using output measures to depict the transfer of control of the services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those services. For arrangements recognized over time, various output measures, including units delivered and time elapsed, are utilized to provide a faithful depiction of the progress towards completion of the performance obligation. Commissions and fees for brokerage services may be invoiced at the inception of the reinsurance period for certain reinsurance brokerage, or more commonly, over the term of the arrangement in installments based on deposit or minimum premiums for most treaty reinsurance arrangements.

Health Solutions includes consulting and brokerage, Human Capital, and Consumer Benefits Solutions. Revenue primarily includes insurance commissions and fees for services rendered. For brokerage commissions, revenue is predominantly recognized at a point in time upon the effective date of the underlying policy (or policies), or for a limited number of arrangements, over the term of the arrangement to depict the transfer of control of the services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those services using input or output measures, including units delivered or time elapsed, to provide a faithful depiction of the progress towards completion of the performance obligation. Revenue from health care exchange arrangements is typically recognized upon successful enrollment of participants. Commissions and fees for brokerage services may be invoiced at the effective date of the underlying policy or over the term of the arrangement in installments during the policy period. Payment terms for other services vary but are typically over the contract term in installments.

Wealth Solutions includes retirement consulting and pension administration, as well as investments. Revenue recognized for these arrangements is predominantly recognized over the term of the arrangement using input or output measures to depict the transfer of control of the services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those services, or for certain arrangements, at a point in time upon completion of the services. For consulting arrangements recognized over time, revenue will be recognized based on a measure of progress that depicts the transfer of control of the services to the customer, utilizing an appropriate input or output measure to provide a reasonable assessment of the progress towards completion of the performance obligation including units delivered or time elapsed. Fees paid by customers for consulting services are typically charged on an hourly, project or fixed-fee basis, and revenue for these arrangements is typically recognized based on time incurred, days elapsed, or reports delivered. Revenue from time-and-materials or cost-plus arrangements are recognized as services are performed using input or output measures to provide a reasonable assessment of the progress towards completion of the performance obligation including hours worked, and revenue for these arrangements is typically recognized based on time and materials incurred. Revenue generated from the Company’s delegated investment business is generally earned as an agreed percentage based on AUM and, to a lesser extent, based on performance fees. Reimbursements received for out-of-pocket expenses are generally recorded as a component of revenue. Payment terms vary but are typically over the contract term in installments.

Share-based Compensation Expense

Share-based payments to employees, including grants of RSUs and PSAs, are measured based on grant date fair value. For purposes of measuring share-based compensation expense, the Company considered whether an adjustment to the observable market price is necessary to reflect material nonpublic information that is known to us at the time the award is granted. No adjustments were necessary for the years ended December 31, 2023, 2022, or 2021. The Company recognizes compensation

expense over the requisite service period for awards expected to ultimately vest. Forfeitures are estimated on the date of grant and revised if actual or expected forfeiture activity differs materially from original estimates.

Pension and Other Postretirement Benefits

The Company records net periodic cost relating to its pension and other postretirement benefit plans based on calculations that include various actuarial assumptions, including discount rates, assumed rates of return on plan assets, inflation rates, mortality rates, compensation increases, and turnover rates. The Company reviews its actuarial assumptions on an annual basis and modifies these assumptions based on current rates and trends. The effects of gains, losses, and prior service costs and credits are amortized over future service periods or future estimated lives if the plans are frozen as reflected in Other income (expense) within the Consolidated Statements of Income. The funded status of each plan, calculated as the fair value of plan assets less the benefit obligation, is reflected in the Company’s Consolidated Statements of Financial Position using a December 31 measurement date.

Earnings per Share

Basic earnings per share is computed by dividing net income available to ordinary shareholders by the weighted-average number of ordinary shares outstanding, including participating securities, which consist of unvested share awards with non-forfeitable rights to dividends. Diluted earnings per share is computed by dividing net income available to ordinary shareholders by the weighted average number of ordinary shares outstanding, which have been adjusted for the dilutive effect of potentially issuable ordinary shares, including certain contingently issuable shares. The diluted earnings per share calculation reflects the more dilutive effect of either (1) the two-class method that assumes that the participating securities have not been exercised, or (2) the treasury stock method.

Potentially issuable shares are not included in the computation of diluted earnings per share if their inclusion would be antidilutive.

Cash and Cash Equivalents and Short-term Investments

Cash and cash equivalents include cash balances and all highly liquid investments with initial maturities of three months or less. Short-term investments generally consist of money market funds. The estimated fair value of Cash and cash equivalents and Short-term investments approximates their carrying values.

At December 31, 2023, Cash and cash equivalents and Short-term investments totaled $1,147 million compared to $1,142 million at December 31, 2022, an increase of $5 million. Of the total balance, $120 million and $115 million was restricted as to its use at December 31, 2023 and 2022, respectively. Included within Short-term investments as of December 31, 2023 and 2022 balances, respectively, were £63.2 million ($80.4 million at December 31, 2023 exchanges rates) and £60.1 million ($72.5 million at December 31, 2022 exchange rates) of operating funds required to be held by the Company in the U.K. by the FCA, a U.K.-based regulator.

Fiduciary Assets and Liabilities

In its capacity as an insurance agent and broker, Aon collects premiums from insureds and, after deducting its commission, remits the premiums to the respective insurers. Aon also collects claims or refunds from insurers on behalf of insureds. Uncollected premiums from insureds and uncollected claims or refunds from insurers are recorded as Fiduciary assets in the Company’s Consolidated Statements of Financial Position. Unremitted insurance premiums and claims are held in a fiduciary capacity and the obligation to remit these funds is recorded as Fiduciary liabilities in the Consolidated Statements of Financial Position.

Funds held on behalf of clients represent fiduciary assets held by Aon for premiums collected from insureds but not yet remitted to insurance companies and claims collected from insurance companies but not yet remitted to insureds of $6.9 billion and $6.4 billion at December 31, 2023 and 2022, respectively. Fiduciary receivables were $9.4 billion and $9.5 billion at December 31, 2023 and 2022, respectively. These funds and a corresponding liability are included in Fiduciary assets and Fiduciary liabilities, respectively, in the accompanying Consolidated Statements of Financial Position.

Allowance for Doubtful Accounts

The Company’s estimate for allowance for credit losses with respect to receivables is based on a combination of factors, including evaluation of forward-looking information, historical write-offs, aging of balances, and other qualitative and quantitative analyses. Receivables, net included an allowance for doubtful accounts of $79 million and $76 million at December 31, 2023 and 2022, respectively.

Fixed Assets

Fixed assets are stated at cost, less accumulated depreciation. Included in this category are certain capitalized costs incurred during the application development stage related to directly obtaining, developing, or enhancing internal use software. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, which are generally as follows:

Asset Description						Estimated Useful Life
Software						Lesser of the life of an associated license, or 4 to 7 years
Leasehold improvements						Lesser of estimated useful life or lease term, not to exceed 10 years
Furniture, fixtures and equipment						4 to 10 years
Computer equipment						4 to 6 years
Buildings						35 years
Automobiles						6 years

Goodwill and Intangible Assets

Goodwill represents the excess of purchase price over the fair value of the net assets acquired in the acquisition of a business. Goodwill is allocated to applicable reporting units. Upon disposition of a business entity, goodwill is allocated to the disposed entity based on the relative fair value of that entity compared to the fair value of the reporting unit in which it was included. Goodwill is not amortized, but instead is tested for impairment at least annually. The goodwill impairment test is performed at the reporting unit level. The Company may initially perform a qualitative analysis to determine if it is more likely than not that the goodwill balance is impaired. If a qualitative assessment is not performed or if a determination is made that it is not more likely than not that the value of the reporting unit exceeds its carrying amount, then the Company will perform a quantitative analysis. If the fair value of a reporting unit is determined to be greater than the carrying value of the reporting unit, goodwill is deemed not to be impaired and no further testing is necessary. If the fair value of a reporting unit is less than the carrying value, a goodwill impairment loss is recognized for the amount that the carrying amount of a reporting unit, including goodwill, exceeds its fair value limited to the total amount of the goodwill allocated to the reporting unit. Any resulting difference will be a charge to Amortization and impairment of intangible assets in the Consolidated Statements of Income in the period in which the determination is made. Fair value is determined using a combination of present value techniques and market prices of comparable businesses.

We classify our intangible assets acquired as either customer-related and contract based or technology and other intangible assets, which includes tradenames. Amortization basis and estimated useful lives by intangible asset type are generally as follows:

Intangible Asset Description						Amortization Basis						Estimated Useful Life
Customer-related and contract-based						In line with underlying cash flows						7 to 20 years
Technology and other intangibles						Straight-line						5 to 7 years
Tradenames						Straight-line						1 to 3 years

Derivatives

Derivative instruments are recognized in the Consolidated Statements of Financial Position at fair value. Where the Company has entered into master netting agreements with counterparties, the derivative positions are netted by counterparties and are reported accordingly in other assets or other liabilities. Changes in the fair value of derivative instruments are recognized in earnings each period, unless the derivative is designated and qualifies as a cash flow or net investment hedge.

The Company has historically designated the following hedging relationships for certain transactions: (1) a hedge of the change in fair value of a recognized asset or liability or firm commitment (“fair value hedge”), (2) a hedge of the variability in cash flows from a recognized variable-rate asset or liability or forecasted transaction (“cash flow hedge”), and (3) a hedge of the net investment in a foreign operation (“net investment hedge”).

In order for a derivative to qualify for hedge accounting, the derivative must be formally designated as a fair value, cash flow, or a net investment hedge by documenting the relationship between the derivative and the hedged item. The documentation must include a description of the hedging instrument, the hedged item, the risk being hedged, Aon’s risk management objective and strategy for undertaking the hedge, and the method for assessing the effectiveness of the hedge. Additionally, the hedge relationship must be expected to be highly effective at offsetting changes in either the fair value or cash flows of the hedged

item at both the inception of the hedge and on an ongoing basis. Aon assesses the ongoing effectiveness of its hedges quarterly or more frequently if facts and circumstances require.

For a derivative designated as a fair value hedging instrument, the gain or loss is recognized in earnings in the period of change together with the offsetting loss or gain on the hedged item attributable to the risk being hedged. The effect is to reflect in earnings the extent to which the hedge is not effective in achieving offsetting changes in fair value. For a cash flow hedge that qualifies for hedge accounting, the change in fair value of a hedging instrument is recognized in Accumulated Other Comprehensive Income and subsequently reclassified to earnings in the same period the hedged item impacts earnings. For a net investment hedge, the change in fair value of the hedging instrument is recognized in Accumulated Other Comprehensive Income as part of the cumulative translation adjustment.

Changes in the fair value of a derivative that is not designated as part of a hedging relationship (commonly referred to as an “economic hedge”) are recorded in Other income (expense) in the Consolidated Statements of Income in the period of change.

The Company discontinues hedge accounting prospectively when (1) the derivative expires or is sold, terminated, or exercised, (2) the qualifying criteria are no longer met, or (3) management removes the designation of the hedging relationship.

Foreign Currency

Certain of the Company’s non-U.S. operations use their respective local currency as their functional currency. These operations that do not have the U.S. dollar as their functional currency translate their financial statements at the current rates of exchange in effect at the balance sheet date and revenues and expenses using rates that approximate those in effect during the period. The resulting translation adjustments are included in Net foreign currency translation adjustments within the Consolidated Statements of Shareholders’ Equity (Deficit). Further, gains and losses from the remeasurement of monetary assets and liabilities that are denominated in a non-functional currency of that entity are included in Other income (expense) within the Consolidated Statements of Income.

Income Taxes

Deferred income taxes are recognized for the effect of temporary differences between financial reporting and tax basis of assets and liabilities and are measured using the enacted marginal tax rates and laws that are currently in effect. The effect on deferred tax assets and liabilities from a change in tax rates is recognized in the period when the rate change is enacted.

Deferred tax assets are reduced by valuation allowances if, based on the consideration of all available evidence, it is more likely than not that some portion of the deferred tax asset will not be realized. Deferred tax assets are realized by having sufficient future taxable income to allow the related tax benefits to reduce taxes otherwise payable. The sources of taxable income that may be available to realize the benefit of deferred tax assets are future reversals of existing taxable temporary differences, future taxable income exclusive of reversing temporary differences and carry-forwards, taxable income in carry-back years, and tax planning strategies that are both prudent and feasible.

The Company recognizes the effect of income tax positions only if sustaining those positions is more likely than not. Tax positions that meet the more likely than not recognition threshold but are not highly certain are initially and subsequently measured based on the largest amount of benefit that is greater than 50% likely of being realized upon settlement with the taxing authority. Only information that is available at the reporting date is considered in the Company’s recognition and measurement analysis, and events or changes in facts and circumstances are accounted for in the period in which the event or change in circumstance occurs.

The Company records penalties and interest related to unrecognized tax benefits in Income taxes in the Company’s Consolidated Statements of Income.

The Company releases income tax effects from Accumulated other comprehensive loss using the portfolio approach.

Leases

The Company leases office facilities, equipment, and automobiles under operating and finance leases. The Company’s lease obligations are primarily for the use of office facilities. The Company evaluates if a leasing arrangement exists upon inception of a contract. A contract contains a lease if the contract conveys the right to control the use of identified tangible assets for a period of time in exchange for consideration. Identified property, plant, or equipment may include a physically distinct portion of a larger asset, or a portion of an asset that represents substantially all of the capacity of the asset but is not physically distinct. The Company assesses whether a contract implicitly contains the right to control the use of a tangible asset that is not already owned. In addition, the Company subleases certain real estate properties to third parties, which are classified as operating leases.

The Company’s leases expire at various dates and may contain renewal, expansion, or termination options. The exercise of lease renewal and expansion options are typically at the Company’s sole discretion and are only included in the determination of the lease term if the Company is reasonably certain to exercise the option. In addition, the Company’s lease agreements typically do not contain any material residual value guarantees or restrictive covenants.

ROU assets and lease liabilities are based on the present value of the minimum lease payments over the lease term. The Company has elected the practical expedient related to lease and non-lease components, as an accounting policy election for all asset classes, which allows a lessee to not separate non-lease components from lease components and instead account for consideration received in a contract as a single lease component. The Company’s lease agreements may include initial direct costs and lease incentives. Initial direct costs are incremental costs of a lease that would not have been incurred if the lease had not been obtained and are included in the measurement of the ROU asset. Payments made to or on behalf of the Company, such as tenant improvement allowances, represent incentives that are considered reductions to the ROU asset and lease expense over the lease term.

The Company made a policy election to not recognize ROU assets and lease liabilities that arise from leases with an initial term of twelve months or less in the Consolidated Statements of Financial Position. However, the Company recognized these lease payments in the Consolidated Statements of Income on a straight-line basis over the lease term and variable lease payments in the period in which the expense was incurred. The Company applies this accounting policy across all classes of underlying assets.

A portion of the Company’s lease agreements include variable lease payments that are not recorded in the initial measurement of the lease liability and ROU asset balances. For real estate arrangements, base rental payments may be escalated according to annual changes in the CPI or other indices. The escalated rental payments based on the estimated CPI at the lease commencement date are included within minimum rental payments; however, changes in CPI are considered variable in nature and are recognized as variable lease costs in the period in which the obligation is incurred. Additionally, real estate lease agreements may include other variable payments related to operating expenses charged by the landlord based on actual expenditures. Information technology equipment agreements may include variable payments based on usage of the equipment. These expenses are also recognized as variable lease costs in the period in which the expense is incurred.

Where Aon has provided notice of cancellation pursuant to a lease agreement, the lease is modified with the associated ROU asset and the related lease liability remeasured, which may include any additional termination penalties incurred that were not previously included within the lease liability. To the extent that the associated ROU assets and lease liabilities are removed, a corresponding gain or loss is recorded.

The Company utilizes discount rates to determine the present value of the lease payments based on information available at the commencement date of the lease. As the rate implicit in each lease is not typically readily available, the Company uses an incremental borrowing rate based on factors such as the lease term and the economic environment where the lease exists to determine the appropriate present value of future lease payments. When determining the incremental borrowing rate, the Company considers the rate of interest it would pay on a secured borrowing in an amount equal to the lease payments for the underlying asset under similar terms.

Operating leases are included in Operating lease ROU assets, Other current liabilities, and Non-current operating lease liabilities in the Consolidated Statements of Financial Position. Finance leases are included in Other non-current assets, Other current liabilities, and Other non-current liabilities in the Consolidated Statements of Financial Position.

Principles of Consolidation

The accompanying Consolidated Financial Statements include the accounts of Aon plc and those entities in which the Company has a controlling financial interest. To determine if Aon holds a controlling financial interest in an entity, the Company first evaluates if it is required to apply the variable interest model to the entity, otherwise, the entity is evaluated under the voting interest model. When Aon holds rights that give it the power to direct the activities of a VIE that most significantly impact the VIE’s economic performance, combined with a variable interest that gives the right to receive potentially significant benefits or the obligation to absorb potentially significant losses, the Company has a controlling financial interest in that VIE. If the Company is the primary beneficiary of a VIE, the Company consolidates the entity and reflects any relevant non-controlling interest of other beneficiaries of that entity on the Statement of Consolidated Financial Position. Aon’s interest in VIEs as of December 31, 2023 was insignificant.

Aon holds a controlling financial interest in entities that are not VIEs when it, directly or indirectly holds more than 50% of the voting rights and the noncontrolling interest holders do not hold substantive participating rights.

New Accounting Pronouncements

Accounting Standards Issued But Not Yet Adopted

Improvements to Reportable Segment Disclosures

In November 2023, the FASB issued new accounting guidance, requiring new segment disclosures under ASC 280, Segment Reporting, including disclosure of significant segment expense categories and amounts that are regularly reported to the CODM and included in the segment’s profit or loss. Additionally, all disclosure requirements under ASC 280 including new requirements under this new guidance, will be required on an interim basis. The new guidance is effective for Aon for the year ended December 31, 2024 and interim periods thereafter, with early adoption permitted. An entity will apply the new guidance on a retrospective basis for all periods presented. The Company is currently evaluating the impact the guidance will have on the Notes to Consolidated Financial Statements.

Improvements to Income Tax Disclosures

In December 2023, the FASB issued new accounting guidance under ASC 740, Income Taxes, which requires additional income tax disclosures on an annual basis, including disaggregation of information presented within the reconciliation of the expected tax to the reported tax by specific categories, with certain reconciling items 5% or greater broken out by nature and/or jurisdiction. The new guidance also requires disclosure of income taxes paid, net of refunds, broken out by federal, state/local and foreign, including disclosure of individual jurisdictions when greater than 5% of total net income taxes paid. The new guidance is effective for Aon for the year ended December 31, 2025, with early adoption permitted. The Company is evaluating the period of adoption and transition approach, as well as the impact the disclosures will have on the Notes to Consolidated Financial Statements.

3. Revenue from Contracts with Customers

Disaggregation of Revenue

The following table summarizes revenue from contracts with customers by principal service line (in millions):

						Years Ended December 31
						2023						2022						2021
Commercial Risk Solutions						$	7,043					$	6,715					$	6,635
Reinsurance Solutions						2,481						2,190						1,997
Health Solutions						2,433						2,224						2,154
Wealth Solutions						1,431						1,367						1,426
Elimination						(12)						(17)						(19)
Total revenue						$	13,376					$	12,479					$	12,193

Consolidated revenue from contracts with customers by geographic area, which is attributed on the basis of where the services are performed, is as follows (in millions):

						Years Ended December 31
						2023						2022						2021
U.S.						$	5,923					$	5,666					$	5,459
Americas other than U.S.						1,260						1,137						1,027
U.K.						1,819						1,660						1,681
Ireland						113						99						127
Europe, Middle East, & Africa other than U.K. and Ireland						2,672						2,443						2,565
Asia Pacific						1,589						1,474						1,334
Total revenue						$	13,376					$	12,479					$	12,193

Contract Costs

Changes in the net carrying amount of costs to fulfill contracts with customers are as follows (in millions):

						2023						2022
Balance at beginning of period						$	355					$	361
Additions						1,532						1,479
Amortization						(1,522)						(1,480)
Impairment						—						—
Foreign currency translation and other						5						(5)
Balance at end of period						$	370					$	355

Changes in the net carrying amount of costs to obtain contracts with customers are as follows (in millions):

						2023						2022
Balance at beginning of period						$	185					$	179
Additions						57						56
Amortization						(51)						(49)
Impairment						—						—
Foreign currency translation and other						4						(1)
Balance at end of period						$	195					$	185

4. Accelerating Aon United Program

In the third quarter of 2023, Aon initiated a three-year restructuring program with the purpose of streamlining the Company’s technology infrastructure, optimizing its leadership structure and resource alignment, and reducing the real estate footprint to align to its hybrid working strategy. The Program will include technology-related costs to facilitate streamlining and simplifying operations, headcount reduction costs, and costs associated with asset impairments, including real estate consolidation costs.

Program charges are recognized within Accelerating Aon United Program expenses on the accompanying Consolidated Statements of Income and consists of the following cost activities:

*•*Technology and other – includes costs associated with actions taken to rationalize applications, such as contract termination fees and other non-capitalizable costs associated with Program initiatives, which include professional service fees.

*•*Workforce optimization – includes costs associated with headcount reduction and other separation-related costs.

*•*Asset impairments – includes non-cash costs associated with impairment of assets, as they are identified, including ROU lease assets, leasehold improvements, and other capitalized assets no longer providing economic benefit.

The Program is currently expected to result in cumulative costs of approximately $1,000 million, consisting of approximately $900 million of cash charges and approximately $100 million of non-cash charges. For the year ended December 31, 2023, total Program costs incurred were $135 million. The Company expects to continue to review the implementation of elements of the Program throughout the course of the Program and, therefore, there may be changes to expected timing, estimates of expected costs, and related savings.

The Company’s unpaid liabilities for charges under the Program are generally included in Accounts payable and accrued liabilities in the Consolidated Statements of Financial Position.

The changes in the Company’s liabilities for the Program as of December 31, 2023 are as follows (in millions):

			Technology and other						Workforce optimization						Asset impairments						Total
Liability Balance as of January 1, 2023			$	—					$	—					$	—					$	—
Charges			14						103						18						135
Cash payments			—						(13)						—						(13)
Foreign currency translation and other			—						1						—						1
Non-cash charges			—						(5)						(18)						(23)
Liability balance as of December 31, 2023			$	14					$	86					$	—					$	100
Total costs incurred from inception to date			$	14					$	103					$	18					$	135

5. Other Financial Data

Consolidated Statements of Income Information

Other Income (Expense)

The components of Other income (expense) are as follows (in millions):

			Years Ended December 31
			2023						2022						2021
Foreign currency remeasurement			$	(99)					$	(14)					$	26
Pension and other postretirement (1)			(98)						(179)						21
Gain from disposals of business			4						54						142
Equity earnings			5						10						8
Financial instruments and other			25						4						(45)
Total			$	(163)					$	(125)					$	152

(1) Refer to Note 12 “Employee Benefits” for further information.

Consolidated Statements of Financial Position Information

Allowance for Doubtful Accounts

Changes in the net carrying amount of allowance for doubtful accounts are as follows (in millions):

			2023						2022						2021
Balance at beginning of period			$	76					$	90					$	98
Provision			13						8						26
Accounts written off, net of recoveries			(11)						(18)						(37)
Foreign currency translation and other			1						(4)						3
Balance at end of period			$	79					$	76					$	90

Other Current Assets

The components of Other current assets are as follows (in millions):

As of December 31			2023						2022
Costs to fulfill contracts with customers (1)			$	370					$	355
Assets held for sale (2)			354						—
Prepaid expenses			100						109
Taxes receivable			35						74
Other			137						108
Total			$	996					$	646

(1)Refer to Note 3 “Revenue from Contracts with Customers” for further information.

(2)Refer to Note 6 “Acquisitions and Dispositions of Businesses” for further information.

Fixed Assets, net

The components of Fixed assets, net are as follows (in millions):

As of December 31			2023						2022
Software			$	983					$	861
Leasehold improvements			430						409
Computer equipment			294						269
Furniture, fixtures, and equipment			269						267
Construction in progress			130						109
Other			30						34
Fixed assets, gross			2,136						1,949
Less: Accumulated depreciation			1,498						1,391
Fixed assets, net			$	638					$	558

Depreciation expense, which includes software amortization, was $167 million, $151 million, and $179 million for the years ended December 31, 2023, 2022, and 2021, respectively.

Other Non-current Assets

The components of Other non-current assets are as follows (in millions):

As of December 31			2023						2022
Costs to obtain contracts with customers (1)			$	195					$	185
Taxes receivable			100						109
Investments			45						60
Leases (2)			26						43
Other			140						112
Total			$	506					$	509

(1) Refer to Note 3 “Revenue from Contracts with Customers” for further information.

(2) Refer to Note 9 “Lease Commitments” for further information.

Other Current Liabilities

The components of Other current liabilities are as follows (in millions):

As of December 31			2023						2022
Taxes payable			$	291					$	193
Deferred revenue (1)			270						250
Leases (2)			182						186
Liabilities held for sale (3)			69						—
Other			1,066						718
Total			$	1,878					$	1,347

(1)$647 million and $653 million was recognized in the Consolidated Statements of Income during the years ended December 31, 2023 and December 31, 2022, respectively.

(2)Refer to Note 9 “Lease Commitments” for further information.

(3)Refer to Note 6 “Acquisitions and Dispositions of Businesses” for further information

Other Non-current Liabilities

The components of Other non-current liabilities are as follows (in millions):

As of December 31			2023						2022
Taxes payable (1)			$	827					$	795
Compensation and benefits payable			59						69
Deferred revenue			33						37
Leases (2)			10						28
Other			145						95
Total			$	1,074					$	1,024

(1)Includes $72 million and $129 million for the non-current portion of the transition tax as of December 31, 2023 and December 31, 2022, respectively. Refer to Note 10 “Income Taxes” for further information on the transition tax.

(2)Refer to Note 9 “Lease Commitments” for further information.

6. Acquisitions and Dispositions of Businesses

Completed Acquisitions

The Company completed three acquisitions during the year ended December 31, 2023 and five acquisitions during the year ended December 31, 2022. The following table includes the preliminary fair values of consideration transferred, assets acquired, and liabilities assumed as a result of the Company’s acquisitions (in millions):

			Year Ended December 31, 2023
Consideration transferred
Cash			$	38
Deferred and contingent consideration			12
Aggregate consideration transferred			$	50
Assets acquired
Goodwill			$	23
Intangible assets			25
Other assets (1)			14
Total assets acquired			62
Liabilities assumed
Total liabilities assumed			12
Net assets acquired			$	50

(1) Includes Cash and cash equivalents of $5 million and an insignificant amount of funds held on behalf of clients.

Intangible assets acquired include customer-related and contract-based assets. The intangible assets acquired as part of business acquisitions in 2023 had a weighted average useful economic life of 8 years. Acquisition-related costs for completed acquisitions incurred and recognized within Other general expense for the year ended December 31, 2023 were insignificant. Total revenue for these acquisitions included in the Company’s Consolidated Statement of Income for the year ended December 31, 2023 was approximately $4 million.

The results of operations of these acquisitions are included in the Consolidated Financial Statements as of the respective acquisition dates. The Company’s results of operations would not have been materially different if these acquisitions had been reported from the beginning of the period in which they were acquired.

2023 Acquisitions

On November 30, 2023, the Company completed the acquisition of 100% of the share capital of Gi&Bi S.r.l., an Italy-based insurance broker specialized in the agricultural business segment.

On August 30, 2023, the Company completed the acquisition of 100% of the share capital of NGS (Uruguay) S.A., a risk management consultant firm in Uruguay.

On June 22, 2023, the Company completed the acquisition of 100% of the share capital of Benefits Corredores de Seguros and Asesorías e Inversiones Benefits, a business that provides health and benefits brokerage and benefit administration in Chile.

2022 Acquisitions

On November 1, 2022, the Company completed the acquisition of 100% of the share capital of E.R.N. Evaluacion de Riesgos Naturales y Antropogenicos, S.A. de C.V., a Mexico-based firm in risk assessment modeling.

On September 12, 2022, the Company completed the purchase of certain assets of Praxiom Risk Management, a provider of professional risk management in the U.S.

On August 1, 2022, the Company completed the purchase of certain assets of U.S. Advisors, Inc., a broker based in the U.S.

On May 3, 2022, the Company completed the acquisition of 100% of the share capital of Karl Köllner group companies, a marine hull broker based in Germany.

On March 1, 2022, the Company completed the acquisition of Tyche, an actuarial software platform based in the U.K.

Completed Dispositions

The Company completed two dispositions during the year ended December 31, 2023. The Company completed three dispositions during the year ended December 31, 2022 and six disposition during the year ended December 31, 2021.

The pretax gains recognized related to dispositions were $4 million, $54 million, and $142 million for the years ended December 31, 2023, December 31, 2022 and December 31, 2021, respectively. Gains recognized as a result of a disposition are included in Other income (expense) in the Consolidated Statements of Income. There were no pretax losses recognized in the Consolidated Statements of Income related to dispositions for the year ended December 31, 2023 and there were insignificant pretax losses recognized for the years ended December 31, 2022, and December 31, 2021, respectively.

Assets and Liabilities Held for Sale

As of December 31, 2023, Aon classified certain assets and liabilities as held for sale, as the Company has committed to a plan

to sell the assets and liabilities within one year. Total assets and liabilities for disposal groups classified as held for sale within Other current assets and Other current liabilities in the Consolidated Statements of Financial Position were $354 million and $69 million, respectively.

Other Significant Activity

On December 19, 2023, Aon entered into a definitive agreement with NFP and the NFP seller, where Aon will acquire NFP for an aggregate purchase price of approximately $7 billion in cash and approximately 20,000,000 class A ordinary shares, nominal value of $0.01, in capital of Aon. The Company expects to fund the cash portion of the consideration with approximately $7 billion of new debt, with $5 billion raised in advance of the closing date and $2 billion raised at close of the Transaction. The Transaction is expected to be completed by mid-2024, subject to satisfaction or waiver of the closing conditions set forth in the Merger Agreement, including applicable regulatory approval.

Subsequent Events

On May 1, 2017, the Company completed the sale of the benefits administration and business process outsourcing business (the “Divested Business”) to an entity controlled by affiliates of The Blackstone Group L.P (the “Buyer”) and certain designated purchases that are direct or indirect subsidiaries of the Buyer. The Buyer purchased all of the outstanding equity interests of the Divested Business, plus certain related assets and liabilities for a purchase price of $4.3 billion in cash paid at closing and deferred consideration of up to $500 million. In the first quarter of 2024, the Company earned $70 million of deferred consideration from the Buyer and the other designated purchasers. No additional significant deferred consideration is expected to be received in any future periods.

7. Goodwill and Other Intangible Assets

The changes in the net carrying amount of goodwill for the years ended December 31, 2023 and 2022, respectively, are as follows (in millions):

Balance as of January 1, 2022			$	8,434
Goodwill related to current year acquisitions			87
Goodwill related to current year disposals			(11)
Foreign currency translation and other			(218)
Balance as of December 31, 2022			$	8,292
Goodwill related to current year acquisitions			23
Goodwill related to current year disposals			(1)
Foreign currency translation and other			100
Balance as of December 31, 2023			$	8,414

Other intangible assets by asset class are as follows (in millions):

			2023																		2022
As of December 31			Gross Carrying Amount						Accumulated Amortization and Impairment						Net Carrying Amount						Gross Carrying Amount						Accumulated Amortization and Impairment						Net Carrying Amount
Customer-related and contract-based (1)			$	1,873					$	1,686					$	187					$	2,207					$	1,833					$	374
Technology and other intangibles			371						324						47						450						377						73
Total			$	2,244					$	2,010					$	234					$	2,657					$	2,210					$	447

(1)As of December 31, 2023, the Company classified $158 million of Intangible assets, net, as Assets held for sale within Other current assets. Refer to Note 6 “Acquisitions and Dispositions of Businesses” for further information.

Amortization and impairment of intangible asset charges from finite lived intangible assets were $89 million, $113 million, and $147 million for the years ended December 31, 2023, 2022, and 2021, respectively.

The estimated future amortization for finite-lived intangible assets as of December 31, 2023 is as follows (in millions):

						Estimated Future Amortization
For the years ended
2024						$	65
2025						54
2026						35
2027						23
2028						17
Thereafter						40
Total						$	234

8. Debt

The following is a summary of outstanding debt (in millions):

As of December 31			2023						2022
Commercial paper			$	597					$	592
4.00% Senior Notes due November 2023			—						350
3.50% Senior Notes due June 2024			600						599
3.875% Senior Notes due December 2025			749						748
2.875% Senior Notes due May 2026 (EUR 500M)			550						530
8.205% Junior Subordinated Notes due January 2027			521						521
2.85% Senior Notes due May 2027			597						596
4.50% Senior Notes due December 2028			348						348
3.75% Senior Notes due May 2029			746						746
2.80% Senior Notes due May 2030			995						994
2.05% Senior Notes due August 2031			397						396
2.60% Senior Notes due December 2031			497						496
5.00% Senior Notes due September 2032			496						495
5.35% Senior Notes due February 2033			744						—
6.25% Senior Notes due September 2040			297						297
4.25% Senior Notes due December 2042			204						203
4.45% Senior Notes due May 2043			247						247
4.60% Senior Notes due June 2044			545						545
4.75% Senior Notes due May 2045			594						594
2.90% Senior Notes due August 2051			592						591
3.90% Senior Notes due February 2052			878						877
Other			5						5
Total debt			11,199						10,770
Less: Short-term debt and current portion of long-term debt			1,204						945
Total long-term debt			$	9,995					$	9,825

Notes

In November 2023, Aon Global Limited’s $350 million 4.00% Senior Notes matured and were repaid in full.

In June 2023, Aon Global Limited’s $600 million 3.50% Senior Notes due June 2024 were classified as Short-term debt and current portion of long-term debt in the Consolidated Statement of Financial Position as the date of maturity is in less than one year.

On February 28, 2023, Aon Corporation and Aon Global Holdings plc co-issued $750 million 5.35% Senior Notes due in February 2033. The Company intends to use the net proceeds from the offering for general corporate purposes.

In November 2022, Aon Corporation’s $500 million 2.20% Senior Notes matured and were repaid in full.

On September 12, 2022, Aon Corporation and Aon Global Holdings plc co-issued $500 million of 5.00% Senior Notes due September 2032. The Company intends to use the net proceeds from the offering for general corporate purposes.

On February 28, 2022, Aon Corporation and Aon Global Holdings plc co-issued $600 million of 2.85% Senior Notes due May 2027 and $900 million of 3.90% Senior Notes due February 2052. The Company intends to use the net proceeds from the offering for general corporate purposes.

Each of the notes issued by Aon Corporation is fully and unconditionally guaranteed by Aon Global Limited, Aon plc, Aon North America, Inc., and Aon Global Holdings plc. Each of the notes issued by Aon Global Limited is fully and unconditionally guaranteed by Aon plc, Aon Global Holdings plc, Aon North America, Inc., and Aon Corporation. Each of the notes co-issued by Aon Corporation and Aon Global Holdings plc is fully and unconditionally guaranteed by Aon plc, Aon

North America, Inc., and Aon Global Limited. All guarantees of Aon plc and Aon Global Limited of the Co-Issued Notes are joint and several as well as full and unconditional. Senior Notes rank pari passu in right of payment with all other present and future unsecured debt which is not expressed to be subordinate or junior in rank to any other unsecured debt of the Co-Issuers. Each of the notes described and identified in the table above contains customary representations, warranties, and covenants, and the Company was in compliance with all such covenants as of December 31, 2023.

Repayments of total debt as of December 31, 2023 are as follows (in millions):

2024			$	1,204
2025			750
2026			552
2027			1,121
2028			350
Thereafter			7,356
Total Repayments			11,333
Unamortized discounts, premiums, and debt issuance costs			(134)
Total Debt			$	11,199

Revolving Credit Facilities

As of December 31, 2023, Aon plc had two primary committed credit facilities outstanding: its $1.0 billion multi-currency U.S. credit facility expiring in September 2027 and its $1.0 billion multi-currency U.S. credit facility expiring in October 2028. In aggregate, these two facilities provide $2.0 billion in available credit.

Each of these primary committed credit facilities includes customary representations, warranties, and covenants, including financial covenants that require Aon to maintain specified ratios of adjusted consolidated EBITDA to consolidated interest expense and consolidated debt to adjusted consolidated EBITDA, in each case, tested quarterly. At December 31, 2023, Aon did not have borrowings under either of these primary committed credit facilities, and was in compliance with the financial covenants and all other covenants contained therein during the rolling year ended December 31, 2023.

Subsequent Events

On February 16, 2024, the Company entered into a credit agreement in which lenders committed to provide a $2.0 billion unsecured term loan facility to Aon North America, Inc. Proceeds will be used to fund, in part, the acquisition of NFP, including the repayment of certain debt of NFP and portions of the related fees and expenses. The borrowings must be made in a single drawing on the closing date of the acquisition. Refer to Note 6 “Acquisitions and Dispositions of Businesses” for additional information.

Commercial Paper

Aon Corporation has established a U.S. commercial paper program (the “U.S. Program”) and Aon Global Holdings plc has established a European multi-currency commercial paper program (the “European Program” and, together with the U.S. Program, the “Commercial Paper Programs”). On December 7, 2023, the Company entered into an agreement increasing the aggregate capacity under the U.S. Program by $250 million. Accordingly, commercial paper may be issued in aggregate principal amounts of up to approximately $1.3 billion under the U.S. Program and €625 million ($690 million at December 31, 2023 exchange rates) under the European Program, not to exceed the amount of the Company’s committed credit facilities, which was $2.0 billion at December 31, 2023. The aggregate capacity of the Commercial Paper Program remains fully backed by the Company’s committed credit facilities. The U.S. Program was fully and unconditionally guaranteed by Aon plc, Aon Global Limited, Aon North America, Inc., and Aon Global Holdings plc and the European Program was fully and unconditionally guaranteed by Aon plc, Aon Global Limited, Aon North America, Inc., and Aon Corporation.

Commercial paper outstanding, which is included in Short-term debt and current portion of long-term debt in the Company’s Consolidated Statements of Financial Position, is as follows (in millions):

As of December 31						2023						2022
Commercial paper outstanding						$	597					$	592

The weighted average commercial paper outstanding and its related interest rates are as follows (in millions, except percentages):

						Years Ended December 31
						2023						2022
Weighted average commercial paper outstanding						$	471					$	499
Weighted average interest rate of commercial paper outstanding						4.93		%				1.42		%

9. Lease Commitments

The classification of operating and finance lease asset and liability balances within the Consolidated Statements of Financial Position are as follows (in millions):

As of December 31						2023			2022
Assets
Operating lease assets			Operating lease right-of-use assets			$	650		$	699
Finance lease assets			Other non-current assets			26			43
Total lease assets						$	676		$	742
Liabilities
Current lease liabilities
Operating			Other current liabilities			$	159		$	163
Finance			Other current liabilities			23			23
Non-current lease liabilities
Operating			Non-current operating lease liabilities			641			693
Finance			Other non-current liabilities			10			28
Total lease liabilities						$	833		$	907

The components of lease costs are as follows (in millions):

			Years Ended December 31
			2023			2022
Operating lease cost			$	183		$	204
Finance lease costs
Amortization of leased assets			19			28
Interest on lease liabilities			—			1
Variable lease cost			44			38
Short-term lease cost (1)			8			11
Sublease income			(13)			(29)
Net lease cost			$	241		$	253

(1) Short-term lease cost does not include expenses related to leases with a lease term of one month or less.

Weighted average remaining lease term and discount rate related to operating and finance leases are as follows:

As of December 31			2023			2022
Weighted average remaining lease term (years)
Operating leases			6.3			6.7
Finance leases			1.5			2.5
Weighted average discount rate
Operating leases			3.6		%	3.1		%
Finance leases			1.0		%	1.0		%

Other cash and non-cash related activities are as follows (in millions):

			Years Ended December 31
			2023			2022
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows for operating leases			$	206		$	231
Financing cash flows for finance leases			$	19		$	14
Non-cash related activities
ROU assets obtained in exchange for new operating lease liabilities			$	112		$	110
Operating lease ROU asset expense (1)			$	141		$	162
Changes in Non-current operating lease liabilities (1)			$	(52)		$	(79)

(1)The Company has presented non-cash changes in Operating lease ROU assets and Non-current operating lease liabilities within Other assets and liabilities in Cash flows from operations within the Consolidated Statements of Cash Flows.

Maturity analysis of operating and finance leases as of December 31, 2023 are as follows (in millions):

			Operating Leases						Finance Leases						Total
2024			$	177					$	23					$	200
2025			162						10						172
2026			140						—						140
2027			122						—						122
2028			98						—						98
Thereafter			190						—						190
Total undiscounted future minimum lease payments			889						33						922
Less: Imputed interest			(89)						—						(89)
Present value of lease liabilities			$	800					$	33					$	833

10. Income Taxes

Income before income tax and the provision for income tax consist of the following (in millions):

			Years Ended December 31
			2023						2022						2021
Income (loss) before income taxes:
Ireland			$	31					$	85					$	15
U.K.			338						502						549
U.S.			219						161						(818)
Other			2,581						2,408						2,185
Total			$	3,169					$	3,156					$	1,931
Income tax expense:
Current:
Ireland			$	4					$	2					$	2
U.K.			185						206						50
U.S. federal			240						195						197
U.S. state and local			74						43						72
Other			411						316						291
Total current tax expense			$	914					$	762					$	612
Deferred tax expense (benefit):
Ireland			$	—					$	—					$	(1)
U.K.			(116)						(152)						131
U.S. federal			(126)						(69)						(83)
U.S. state and local			(39)						(21)						(30)
Other			(92)						(10)						(6)
Total deferred tax expense (benefit)			$	(373)					$	(252)					$	11
Total income tax expense			$	541					$	510					$	623

Income before income taxes shown above may, in some cases, be subject to taxation in more than one country, and as a result the income tax provision shown above as Ireland, U.K., U.S. or Other may not correspond to the geographic attribution of the earnings.

The Company performs a reconciliation of the income tax provisions based on its domicile and statutory rate at each reporting period. The reconciliation of the income tax provisions based on the Irish statutory corporate tax rate of 25% to the provisions reflected in the Consolidated Financial Statements is as follows:

			Years Ended December 31
			2023						2022						2021
Statutory tax rate			25.0%						25.0%						25.0%
U.S. state income taxes, net of U.S. federal benefit			0.6						0.4						1.5
Taxes on international operations (1)			(11.2)						(11.6)						(15.4)
Nondeductible expenses			3.2						2.4						3.3
Adjustments to prior year tax requirements			0.5						(7.0)						(0.2)
Deferred tax adjustments, including statutory rate changes			(0.3)						(0.5)						3.2
Deferred tax adjustments, international earnings			0.7						0.2						1.8
Adjustments to valuation allowances			(2.5)						1.9						(0.2)
Change in uncertain tax positions			2.6						8.6						2.1
Excess tax benefits related to shared based compensation (2)			(1.6)						(1.5)						(2.4)
Capital and other losses			—						(1.4)						—
Non-deductible transaction costs			—						—						1.1
Non-deductible termination fee			—						—						12.9
Other — net			0.1						(0.3)						(0.4)
Effective tax rate			17.1%						16.2%						32.3%

(1)The Company determines the adjustment for taxes on international operations based on the difference between the statutory tax rate applicable to earnings in each foreign jurisdiction and the enacted rate of 25.0%, 25.0% and 25.0% at December 31, 2023, 2022, and 2021, respectively. The benefit to the Company’s effective income tax rate from taxes on international operations relates to benefits from lower-taxed global operations, primarily due to the use of global funding structures and the tax holiday in Singapore.

(2)Excess tax benefits and deficiencies from share-based payment transactions are recognized as income tax expense or benefit in the Company’s Consolidated Statements of Income.

The Company has elected to account for GILTI in the period in which it is incurred, and therefore has not provided deferred tax impacts of GILTI in its Consolidated Financial Statements.

The components of the Company’s deferred tax assets and liabilities are as follows (in millions):

As of December 31			2023						2022
Deferred tax assets:
Net operating loss, capital loss, interest, and tax credit carryforwards			$	1,049					$	952
Employee benefit plans			337						297
Lease liabilities			164						178
Other accrued expenses			155						100
Federal and state benefit of interest from uncertain tax positions			75						57
Accrued interest			52						—
Deferred revenue			25						26
Investment basis differences			49						30
Other (1)			40						39
Total			1,946						1,679
Valuation allowance on deferred tax assets			(197)						(275)
Total			$	1,749					$	1,404
Deferred tax liabilities:
Intangibles and property, plant and equipment			$	(254)					$	(258)
Deferred costs			(149)						(147)
Lease right-of-use asset			(135)						(151)
Unremitted earnings			(44)						(38)
Other accrued expenses			(20)						(20)
Unrealized foreign exchange gains			(18)						(23)
Other			(49)						(42)
Total			$	(669)					$	(679)
Net deferred tax asset			$	1,080					$	725

(1)$1 million of Lease and service guarantees reported for the year-ended Dec 31, 2022 have been reclassified into “Other”.

Deferred income taxes (assets and liabilities have been netted by jurisdiction) have been classified in the Consolidated Statements of Financial Position as follows (in millions):

As of December 31			2023						2022
Deferred tax assets — non-current			$	1,195					$	824
Deferred tax liabilities — non-current			(115)						(99)
Net deferred tax asset			$	1,080					$	725

In assessing the realizability of deferred tax assets, the Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized and adjusts the valuation allowance accordingly. Considerations with respect to the realizability of deferred tax assets include the period of expiration of the deferred tax asset, historical earnings and projected future taxable income by jurisdiction as well as tax liabilities for the tax jurisdiction to which the tax asset relates. Significant management judgment is required in determining the assumptions and estimates related to the amount and timing of future taxable income. Valuation allowances have been established primarily with regard to the tax benefits of certain tax credits, net operating loss carryforwards, and capital loss carryforwards. Valuation allowances decreased by $78 million as of December 31, 2023, when compared to December 31, 2022. The change is primarily attributable to a decrease in valuation allowances related to capital loss carryforwards that expired and certain net operating loss carryforwards.

The Company generally intends to limit distributions from foreign subsidiaries in excess of U.S. tax earnings and profits (except where distributions would be limited by available cash) and to limit repatriations from certain other jurisdictions that would otherwise generate a U.S. tax liability. As of December 31, 2023, the Company has accrued $44 million for local country income taxes, withholding taxes and state income taxes on those undistributed earnings that are not indefinitely reinvested. The Company has not provided for deferred taxes on outside basis differences in our investments in our foreign subsidiaries that are unrelated to these accumulated undistributed earnings, as these outside basis differences are indefinitely reinvested. A

determination of the unrecognized deferred taxes related to these other components of our outside basis differences is not practicable.

The Company had the following carryforwards (in millions):

As of December 31			2023						2022
U.K.
Operating loss carryforwards			$	1,033					$	608
Capital loss carryforwards			$	550					$	533
U.S.
Federal operating loss carryforwards			$	1					$	1
Federal capital loss carryforwards			$	—					$	112
Federal interest carryforwards			$	2,303					$	2,269
Federal foreign tax credit carryforwards			$	24					$	20
State operating loss carryforwards			$	493					$	473
State capital loss carryforwards			$	—					$	123
State interest carryforwards			$	1,209					$	1,187
Other Non-U.S.
Operating loss carryforwards			$	461					$	490
Capital loss carryforwards			$	7					$	8
Interest carryforwards			$	129					$	26
Other carryforwards			$	3					$	5

The U.K. operating losses and capital losses have an indefinite carryforward period. The federal operating loss carryforwards generated through December 31, 2017 expire at various dates between 2034 and 2036 while federal operating loss carryforwards generated after this date have indefinite carryforward periods. State net operating losses as of December 31, 2023 have various carryforward periods and will begin to expire in 2024. Federal and state interest carryforwards have indefinite carryforward periods. Foreign tax credits can be carried forward for ten years and will begin to expire in 2029. Operating, capital losses, and other carryforwards in other non-U.S. jurisdictions have various carryforward periods and will begin to expire in 2024. The interest carryforwards in other non-U.S. jurisdictions have an indefinite carryforward period.

During 2012, the Company was granted a tax holiday for the period from October 1, 2012 through September 30, 2022, with respect to withholding taxes and certain income derived from services in Singapore. The Company has been granted a new incentive for the period October 1, 2022 to September 30, 2032. The new incentive provides for a reduced withholding tax rate and a reduced tax rate on certain income derived from services in Singapore, as long as certain conditions are met.

The benefit realized was approximately $93 million, $115 million, and $104 million during the years ended December 31, 2023, 2022, and 2021, respectively. The impact of this tax holiday on diluted earnings per share was $0.45, $0.54, and $0.46 during the years ended December 31, 2023, 2022, and 2021, respectively.

Uncertain Tax Positions

The following is a reconciliation of the Company’s beginning and ending amount of uncertain tax positions (in millions):

			2023						2022
Balance at January 1			$	601					$	347
Additions based on tax positions related to the current year			40						35
Additions for tax positions of prior years			2						226
Reductions for tax positions of prior years			(3)						(1)
Settlements			—						(1)
Business combinations			—						—
Lapse of statute of limitations			(3)						(5)
Foreign currency translation			—						—
Balance at December 31			$	637					$	601

The Company’s liability for uncertain tax positions as of December 31, 2023, 2022, and 2021, includes $570 million, $535 million, and $295 million, respectively, related to amounts that would impact the effective tax rate if recognized. It is possible that the amount of unrecognized tax benefits may change in the next twelve months; however, the Company does not expect the change to have a significant impact on its consolidated statements of income or consolidated balance sheets. These changes may be the result of settlements of ongoing audits. At this time, an estimate of the range of the reasonably possible outcomes within the next twelve months cannot be made.

The Company recognizes interest and penalties related to uncertain tax positions in its provision for income taxes. The Company accrued potential interest and penalties of $62 million, $40 million, and $22 million in 2023, 2022, and 2021, respectively. The Company recorded a liability for interest and penalties of $244 million, $181 million, and $142 million as of December 31, 2023, 2022, and 2021, respectively.

The Company and its subsidiaries file income tax returns in their respective jurisdictions. The Company has substantially concluded all U.S. federal income tax matters for years through 2007. Material U.S. state and local income tax jurisdiction examinations have been concluded for years through 2015. The Company has concluded income tax examinations in its primary non-U.S. jurisdictions through 2008.

11. Shareholders’ Equity (Deficit)

Distributable Profits

The Company is required under Irish law to have available “distributable profits” to make share repurchases or pay dividends to shareholders. Distributable profits are created through the earnings of the Irish parent company and, among other methods, through intercompany dividends or a reduction in share capital approved by the High Court of Ireland. Distributable profits are not linked to a U.S. GAAP reported amount (e.g., accumulated deficit). As of December 31, 2023 and 2022, the Company had distributable profits in excess of $27.5 billion and $29.0 billion, respectively. We believe that we have the ability to create sufficient distributable profits for the foreseeable future.

Ordinary Shares

Aon has a share repurchase program authorized by the Company’s Board of Directors. The Repurchase Program was established in April 2012 with $5.0 billion in authorized repurchases and was increased by $5.0 billion in authorized repurchases in each of November 2014, June 2017, and November 2020, and by $7.5 billion in February 2022 for a total of $27.5 billion in repurchase authorizations.

Under the Repurchase Program, the Company’s class A ordinary shares may be repurchased through the open market or in privately negotiated transactions, from time to time, based on prevailing market conditions and will be funded from available capital.

The following table summarizes the Company’s share repurchase activity (in millions, except per share data):

						Years Ended December 31
						2023						2022
Shares repurchased						8.4						11.1
Average price per share						$	321.52					$	289.76
Repurchase costs recorded to Accumulated deficit						$	2,700					$	3,203

At December 31, 2023, the remaining authorized amount for share repurchases under the Repurchase Program was approximately $3.3 billion. Under the Repurchase Program, the Company has repurchased a total of 169.1 million shares for an aggregate cost of approximately $24.2 billion.

Weighted Average Ordinary Shares

Weighted average ordinary shares outstanding are as follows (in millions):

			Years Ended December 31
			2023						2022						2021
Basic weighted average ordinary shares outstanding			203.5						211.7						224.7
Dilutive effect of potentially issuable shares			1.5						1.5						1.4
Diluted weighted average ordinary shares outstanding			205.0						213.2						226.1

Potentially issuable shares are not included in the computation of Diluted net income per share attributable to Aon shareholders if their inclusion would be antidilutive. There were no shares excluded from the calculation in 2023, 0.8 million shares excluded in 2022, and 0.3 million shares excluded in 2021.

Accumulated Other Comprehensive Loss

Changes in Accumulated other comprehensive loss by component, net of related tax, are as follows (in millions):

			Change in Fair Value of Financial Instruments (1)						Foreign Currency Translation Adjustments						Postretirement Benefit Obligation (2)						Total
Balance at December 31, 2020			$	1					$	(1,045)					$	(2,817)					$	(3,861)
Other comprehensive income (loss) before reclassifications:
Other comprehensive income (loss) before reclassifications			—						(290)						227						(63)
Tax benefit			—						2						(58)						(56)
Other comprehensive income (loss) before reclassifications, net			—						(288)						169						(119)
Amounts reclassified from accumulated other comprehensive income (loss):
Amounts reclassified from accumulated other comprehensive income			2						—						142						144
Tax expense			(1)						—						(34)						(35)
Amounts reclassified from accumulated other comprehensive income, net			1						—						108						109
Net current period other comprehensive income (loss)			1						(288)						277						(10)
Balance at December 31, 2021			$	2					$	(1,333)					$	(2,540)					$	(3,871)
Other comprehensive income (loss) before reclassifications:
Other comprehensive income (loss) before reclassifications			(15)						(528)						(569)						(1,112)
Tax benefit (expense)			4						—						149						153
Other comprehensive income (loss) before reclassifications, net			(11)						(528)						(420)						(959)
Amounts reclassified from accumulated other comprehensive income (loss):
Amounts reclassified from accumulated other comprehensive income (loss)			(2)						—						282						280
Tax expense			—						—						(73)						(73)
Amounts reclassified from accumulated other comprehensive income (loss), net			(2)						—						209						207
Net current period other comprehensive income (loss)			(13)						(528)						(211)						(752)
Balance at December 31, 2022			$	(11)					$	(1,861)					$	(2,751)					$	(4,623)
Other comprehensive income (loss) before reclassifications:
Other comprehensive loss before reclassifications			8						278						(212)						74
Tax benefit (expense)			(1)						(1)						54						52
Other comprehensive loss before reclassifications, net			7						277						(158)						126
Amounts reclassified from accumulated other comprehensive income (loss):
Amounts reclassified from accumulated other comprehensive income			8						—						159						167
Tax expense			(2)						—						(41)						(43)
Amounts reclassified from accumulated other comprehensive income, net			6						—						118						124
Net current period other comprehensive income (loss)			13						277						(40)						250
Balance at December 31, 2023			$	2					$	(1,584)					$	(2,791)					$	(4,373)

(1)Reclassifications from this category included in Accumulated other comprehensive loss are recorded in Total revenue, Interest expense, and Compensation and benefits in the Consolidated Statements of Income. Refer to Note 14 “Derivatives and Hedging” for further information regarding the Company’s derivative and hedging activity.

(2)Reclassifications from this category included in Accumulated other comprehensive loss are recorded in Other income (expense) in the Consolidated Statements of Income.

12. Employee Benefits

Defined Contribution Savings Plans

Aon maintains defined contribution savings plans for the benefit of its employees. The expense recognized for these plans is included in Compensation and benefits in the Consolidated Statements of Income. The expense for the significant plans in the U.S., U.K., Netherlands, and Canada is as follows (in millions):

			Years Ended December 31
			2023						2022						2021
U.S.			$	114					$	108					$	103
U.K.			52						47						46
Netherlands and Canada			33						33						35
Total			$	199					$	188					$	184

Pension and Other Postretirement Benefits

The Company sponsors defined benefit pension and postretirement health and welfare plans that provide retirement, medical, and life insurance benefits. The postretirement health care plans are contributory, with retiree contributions adjusted annually, and the life insurance and pension plans are generally noncontributory. The significant U.S., U.K., Netherlands, and Canada pension plans are closed to new entrants.

Pension Plans

The following tables provide a reconciliation of the changes in the projected benefit obligations and fair value of assets for the years ended December 31, 2023 and 2022, and a statement of the funded status as of December 31, 2023 and 2022, for Aon’s significant U.K., U.S., and other major pension plans, which are located in the Netherlands and Canada. These plans represent approximately 88% of the Company’s projected benefit obligations.

			U.K.												U.S.												Other
(millions)			2023						2022						2023						2022						2023						2022
Change in projected benefit obligation
At January 1			$	2,946					$	4,919					$	2,180					$	3,164					$	1,094					$	1,531
Service cost			—						1						—						—						—						—
Interest cost			147						83						103						73						41						19
Plan amendment			5						—						—						—						—						—
Settlements			—						—						3						(283)						(63)						—
Actuarial (gain) loss			143						(1,418)						51						(607)						63						(322)
Benefit payments			(173)						(195)						(138)						(167)						(44)						(45)
Foreign currency impact			165						(444)						—						—						38						(89)
As of December 31			$	3,233					$	2,946					$	2,199					$	2,180					$	1,129					$	1,094
Accumulated benefit obligation at end of year			$	3,233					$	2,946					$	2,199					$	2,180					$	1,117					$	1,079
Change in fair value of plan assets
At January 1			$	3,537					$	6,246					$	1,481					$	2,378					$	1,032					$	1,430
Actual return on plan assets			211						(1,961)						121						(484)						93						(284)
Employer contributions			4						7						32						37						14						15
Settlements			—						—						3						(283)						(63)						—
Benefit payments			(173)						(195)						(138)						(167)						(44)						(45)
Foreign currency impact			196						(559)						—						—						37						(83)
As of December 31			$	3,775					$	3,537					$	1,499					$	1,481					$	1,069					$	1,032
Market related value at end of year			$	3,775					$	3,537					$	1,788					$	1,794					$	1,069					$	1,032
Amount recognized in Statement of Financial Position as of December 31
Funded status			$	542					$	591					$	(700)					$	(699)					$	(60)					$	(62)
Unrecognized prior-service cost			39						35						—						—						(5)						(6)
Unrecognized loss			1,870						1,726						1,319						1,305						436						443
Net amount recognized			$	2,451					$	2,352					$	619					$	606					$	371					$	375

In 2023, the net actuarial losses increased the benefit obligation primarily due to the decrease in discount rates. During 2022, the benefit obligation decreased primarily as a result of increases in the discount rates. In 2022, the value of plan assets decreased as a result of negative asset returns, predominately in the U.K, and overall weaker exchange rates versus the U.S. Dollar compared to prior year. The U.K. pension assets are concentrated in fixed income and annuities which were disproportionately negatively impacted by the decreasing interest rate environment. The U.K. hedging strategy continues to perform as expected and the related pension plans remain over-funded.

In May 2023, to further its pension de-risking strategy, the Company settled certain pension obligations in the Netherlands through the purchase of annuities, where certain pension assets were liquidated to purchase the annuities. The transaction settled $63 million of benefit obligations using $63 million of assets.

In November 2022, to further its pension de-risking strategy the Company purchased an annuity for portions of its U.S. pension plans that will settle certain obligations. The transaction settled $280 million of benefit obligations using $280 million of assets.

Amounts recognized in the Consolidated Statements of Financial Position consist of (in millions):

			U.K.												U.S.												Other
			2023						2022						2023						2022						2023						2022
Prepaid benefit cost (1)			$	570					$	612					$	—					$	—					$	1					$	—
Accrued benefit liability - current (2)			(1)						(1)						(42)						(42)						(4)						(5)
Accrued benefit liability - non-current (3)			(27)						(20)						(658)						(657)						(57)						(57)
Accumulated other comprehensive loss			1,909						1,761						1,319						1,305						431						437
Net amount recognized			$	2,451					$	2,352					$	619					$	606					$	371					$	375

(1)Included in Prepaid pension.

(2)Included in Other current liabilities.

(3)Included in Pension, other postretirement, and postemployment liabilities.

Amounts recognized in Accumulated other comprehensive loss (income) that have not yet been recognized as components of net periodic benefit cost at December 31, 2023 and 2022 consist of (in millions):

			U.K.												U.S.												Other
			2023						2022						2023						2022						2023						2022
Net loss			$	1,870					$	1,726					$	1,319					$	1,305					$	436					$	443
Prior service cost (income)			39						35						—						—						(5)						(6)
Total			$	1,909					$	1,761					$	1,319					$	1,305					$	431					$	437

In 2023, U.S. plans with a PBO and an ABO in excess of the fair value of plan assets had a PBO of $2.2 billion, an ABO of $2.2 billion, and plan assets with a fair value of $1.5 billion. U.K. plans with a PBO and an ABO in excess of the fair value of plan assets had a PBO of $124 million, an ABO of $124 million and, plan assets with a fair value of $96 million. Other plans with a PBO in excess of the fair value of plan assets had a PBO of $1.0 billion and plan assets with a fair value of $0.9 billion, and other plans with an ABO in excess of the fair value of plan assets had an ABO of $233 million and plan assets with a fair value of $178 million.

In 2022, U.S. plans with a PBO and an ABO in excess of the fair value of plan assets had a PBO of $2.2 billion, an ABO of $2.2 billion, and plan assets with a fair value of $1.5 billion. U.K. plans with a PBO and an ABO in excess of the fair value of plan assets had a PBO of $114 million, an ABO of $114 million and, plan assets with a fair value of $93 million. Other plans with a PBO in excess of the fair value of plan assets had a PBO of $1.1 billion and plan assets with a fair value of $1.0 billion, and other plans with an ABO in excess of the fair value of plan assets had an ABO of $220 million and plan assets with a fair value of $116 million.

Service cost is reported in Compensation and benefits and all other components are reported in Other income (expense) as follows (in millions):

			U.K.																		U.S.																		Other
			2023						2022						2021						2023						2022						2021						2023						2022						2021
Service cost			$	—					$	1					$	1					$	—					$	—					$	—					$	—					$	—					$	—
Interest cost			147						83						65						103						73						57						41						19						12
Expected return on plan assets, net of administration expenses			(190)						(134)						(137)						(119)						(108)						(130)						(48)						(33)						(32)
Amortization of prior-service cost			2						2						2						—						—						—						—						—						—
Amortization of net actuarial loss			75						29						32						34						61						78						13						13						15
Net periodic benefit (income) cost			34						(19)						(37)						18						26						5						6						(1)						(5)
Settlement expense			—						—						5						—						170						—						27						—						—
Total net periodic benefit cost (income)			$	34					$	(19)					$	(32)					$	18					$	196					$	5					$	33					$	(1)					$	(5)

The Company uses a full-yield curve approach in the estimation of the service and interest cost components of net periodic pension and postretirement benefit cost for its major pension and other postretirement benefit plans. This estimation was

obtained by applying the specific spot rates along the yield curve used in the determination of the benefit obligation to the relevant projected cash flows.

In May 2023, to further its pension de-risking strategy, the Company settled certain pension obligations in the Netherlands through the purchase of an annuity. A non-cash settlement charge of approximately $27 million was recognized.

In November 2022, to further its pension de-risking strategy the Company purchased an annuity for portions of its U.S. pension plans that will settle certain obligations. This triggered settlement accounting which required immediate recognition of a portion of the accumulated losses associated with the plan. Consequently, the Company recognized a non-cash settlement charge of approximately $170 million in 2022.

Transfer payments from certain U.K. pension plans exceeded the plan’s service and interest cost in 2021. This triggered settlement accounting which required immediate recognition of a portion of the accumulated losses associated with the plan. Consequently, the Company recognized a non-cash settlement charge for approximately £3 million in 2021 ($5 million using December 31, 2021 exchange rates).

The weighted-average assumptions used to determine benefit obligations are as follows:

			U.K.												U.S. (1)												Other
			2023						2022						2023						2022						2023						2022
Discount rate			4.58%						4.89%						4.60 - 4.84%						4.82 - 5.03%						2.95 - 4.65%						3.23 - 5.19%
Rate of compensation increase			3.38 - 3.88%						3.59 - 4.09%						N/A						N/A						1.00 - 3.00%						1.00 - 3.00%
Underlying price inflation			2.33%						2.44%						N/A						N/A						2.00%						2.00%

(1)U.S. pension plans are frozen and therefore not impacted by compensation increases or price inflation.

The weighted-average assumptions used to determine the net periodic benefit cost are as follows:

			U.K.																		U.S.																		Other
			2023						2022						2021						2023						2022						2021						2023						2022						2021
Discount rate			4.95%						1.85%						1.20%						4.80 - 4.91%						1.67 - 2.25%						1.12 - 1.79%						3.35 - 5.15%						0.84 - 2.58%						0.28 - 2.00%
Expected return on plan assets, net of administration expenses			5.34%						2.34%						2.04%						6.82%						2.03 - 5.28%						2.65 - 6.56%						4.20 - 4.85%						1.80 - 3.15%						1.70 - 2.65%
Rate of compensation increase			3.59 - 4.09%						3.62 - 4.12%						3.22 - 3.72%						N/A						N/A						N/A						1.00 - 3.00%						1.00 - 3.00%						1.00 - 3.00%

Expected Return on Plan Assets

To determine the expected long-term rate of return on plan assets, the historical performance, investment community forecasts, and current market conditions are analyzed to develop expected returns for each asset class used by the plans. The expected returns for each asset class are weighted by the target allocations of the plans. The expected return of 6.82% on U.S. plan assets reflects a portfolio that is seeking asset growth through a higher equity allocation while maintaining prudent risk levels. The portfolio contains certain assets that have historically resulted in higher returns, as well as other financial instruments to minimize downside risk.

No plan assets are expected to be returned to the Company during 2024.

Fair value of plan assets

The Company determined the fair value of plan assets through numerous procedures based on the asset class and available information. Refer to Note 15 “Fair Value Measurements and Financial Instruments” for a description of the procedures performed to determine the fair value of the plan assets.

The fair values of the Company’s U.S. pension plan assets at December 31, 2023 and December 31, 2022, by asset category, are as follows (in millions):

									Fair Value Measurements Using
Asset Category			Balance at December 31, 2023						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Cash and cash equivalents (1)			$	35					$	35					$	—					$	—
Equity investments:
Equity securities			74						74						—						—
Equity derivatives			—						—						—						—
Pooled funds (2)			341						—						—						—
Fixed income investments:
Corporate bonds			124						—						124						—
Government and agency bonds			272						232						40						—
Fixed Income Derivatives			2						—						2						—
Pooled funds (2)			373						—						—						—
Other investments:
Real estate (2) (3)			93						—						—						—
Alternative investments (2) (4)			185						—						—						—
Total			$	1,499					$	341					$	166					$	—

									Fair Value Measurements Using
Asset Category			Balance at December 31, 2022						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Cash and cash equivalents (1)			$	42					$	42					$	—					$	—
Equity investments:
Equity securities			64						64						—						—
Equity derivatives			(6)						—						(6)						—
Pooled funds (2)			293						—						—						—
Fixed income investments:
Corporate bonds			192						—						192						—
Government and agency bonds			149						124						25						—
Pooled funds (2)			507						—						—						—
Other investments:
Real estate (2)(3)			113						—						—						—
Alternative investments (2) (4)			127						—						—						—
Total			$	1,481					$	230					$	211					$	—

(1)Consists of cash and institutional short-term investment funds.

(2)Certain investments measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in the above table are intended to permit reconciliation of the fair values to the amounts presented in the plan assets contained in this Note.

(3)Consists of property funds and trusts holding direct real estate investments.

(4)Consists of limited partnerships, private equity, and hedge funds.

The fair values of the Company’s major U.K. pension plan assets at December 31, 2023 and December 31, 2022, by asset category, are as follows (in millions):

									Fair Value Measurements Using
			Balance at December 31, 2023						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Cash and cash equivalents (1)			$	273					$	273					$	—					$	—
Equity investments:
Pooled funds (2)			—						—						—						—
Fixed income investments:
Derivatives (3)			(255)						—						(255)						—
Government and agency bonds			1,570						1,570						—						—
Annuities			1,510						—						—						1,510
Pooled funds (2)			160						—						—						—
Other investments:
Real estate (2) (4)			92						—						—						—
Pooled funds (2) (5)			425						—						—						—
Total			$	3,775					$	1,843					$	(255)					$	1,510

									Fair Value Measurements Using
			Balance at December 31, 2022						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Cash and cash equivalents (1)			$	336					$	336					$	—					$	—
Equity investments:
Pooled funds (2)			—						—						—						—
Fixed income investments:
Derivatives (3)			(548)						—						(548)						—
Government and agency bonds			1,593						1,593						—						—
Annuities			1,403						—						—						1,403
Pooled funds (2)			139						—						—						—
Other investments:
Real estate (2) (4)			97						—						—						—
Pooled funds (2) (5)			517						—						—						—
Total			$	3,537					$	1,929					$	(548)					$	1,403

(1)Consists of cash and institutional short-term investment funds.

(2)Certain investments measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in the above table are intended to permit reconciliation of the fair values to the amounts presented in the plan assets contained in this Note.

(3)Consists of equity securities and equity derivatives, including repurchase agreements.

(4)Consists of property funds and trusts holding direct real estate investments.

(5)Consists of multi-strategy limited partnerships, private equity, hedge funds, and collective investment schemes with a diversified portfolio of cash, equities, equity related securities, derivatives, and/or fixed income securities.

The following table presents the changes in the Level 3 fair-value category in the Company’s U.K. pension plans for the years ended December 31, 2023 and December 31, 2022 (in millions):

Fair Value Measurements Using Level 3 Inputs			Annuities
Balance at January 1, 2022			$	2,305
Actual return on plan assets:
Relating to assets still held at December 31, 2022			(674)
Purchase, sales and settlements-net			—
Foreign exchange			(228)
Balance at December 31, 2022			1,403
Actual return on plan assets:
Relating to assets still held at December 31, 2023			30
Purchases, sales and settlements-net			—
Foreign exchange			77
Balance at December 31, 2023			$	1,510

The fair values of the Company’s other major pension plan assets at December 31, 2023 and December 31, 2022, by asset category, are as follows (in millions):

									Fair Value Measurements Using
			Balance at December 31, 2023						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Cash and cash equivalents (1)			$	26					$	26					$	—					$	—
Equity investments:
Equity securities			53						53						—						—
Pooled funds (2)			204						—						—						—
Fixed income investments:
Government and agency bonds			243						243						—						—
Derivatives			(3)						—						(3)						—
Pooled funds (2)			490						—						—						—
Other investments:
Alternative investments (2) (3)			47						—						—						—
Real estate (2) (4)			9						—						—						—
Total			$	1,069					$	322					$	(3)					$	—

									Fair Value Measurements Using
			Balance at December 31, 2022						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Cash and cash equivalents (1)			$	30					$	30					$	—					$	—
Equity investments:
Equity securities			53						53						—						—
Pooled funds (2)			211						—						—						—
Fixed income investments:
Government and agency bonds			225						225						—						—
Derivatives			(3)						—						(3)
Pooled funds (2)			462						—						—						—
Other investments:
Alternative investments (2) (3)			42						—						—						—
Real estate (2) (4)			12						—						—						—
Total			$	1,032					$	308					$	(3)					$	—

(1)Consists of cash and institutional short-term investment funds.

(2)Certain investments measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in the above table are intended to permit reconciliation of the fair values to the amounts presented in the plan assets contained in this Note.

(3)Consists of limited partnerships, private equity, and hedge funds.

(4)Consists of property funds and trusts holding direct real estate investments.

Investment Policy and Strategy

The U.S. investment policy, as established by the RPGIC, seeks reasonable asset growth at prudent risk levels within weighted average target allocations. At December 31, 2023, the weighted average targeted allocation for the U.S. plans was 28% for equity investments, 50% for fixed income investments, and 22% for other investments. Aon believes that plan assets are well-diversified and are of appropriate quality. The investment portfolio asset allocation is reviewed quarterly and re-balanced to be within policy target allocations. The investment policy is reviewed at least annually and revised, as deemed appropriate by the RPGIC. The investment policies for international plans are generally established by the local pension plan trustees and seek to maintain the plans’ ability to meet liabilities and to comply with local minimum funding requirements. Plan assets are invested in diversified portfolios that provide adequate levels of return at an acceptable level of risk. The investment policies are reviewed at least annually and revised, as deemed appropriate to ensure that the objectives are being met. At December 31, 2023, the weighted average targeted allocation for the U.K. and non-U.S. plans was 6% for equity investments, 89% for fixed income investments, and 5% for other investments.

Cash Flows

Contributions

Based on current assumptions, in 2024, the Company expects to contribute approximately $2 million, $53 million, and $13 million to its significant U.K., U.S., and other major pension plans, respectively.

Estimated Future Benefit Payments

Estimated future benefit payments for plans, not including voluntary one-time lump sum payments, are as follows at December 31, 2023 (in millions):

						U.K.						U.S.						Other
2024						$	165					$	160					$	47
2025						$	169					$	159					$	48
2026						$	174					$	164					$	50
2027						$	179					$	166					$	51
2028						$	184					$	159					$	52
2029 - 2033						$	966					$	756					$	275

U.S. and Canadian Other Postretirement Benefits

The following table provides an overview of the accumulated PBO, fair value of plan assets, funded status and net amount recognized as of December 31, 2023 and 2022 for the Company’s other significant postretirement benefit plans located in the U.S. and Canada (in millions):

			2023						2022
Accumulated projected benefit obligation			$	91					$	83
Fair value of plan assets			15						14
Funded status			(76)						(69)
Unrecognized prior-service credit			—						(1)
Unrecognized (gain) loss			(16)						(19)
Net amount recognized			$	(92)					$	(89)

Other information related to the Company’s other postretirement benefit plans are as follows:

			2023						2022						2021
Net periodic benefit cost recognized (millions)			$4						$3						$5
Weighted-average discount rate used to determine future benefit obligations			4.65 - 4.87%						4.94 -5.19%						2.52 -3.06%
Weighted-average discount rate used to determine net periodic benefit costs			4.92 - 5.17%						1.97 -2.69%						1.45 - 2.68%

Based on current assumptions, the Company expects:

• The amount in Accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost during 2024 is $0.7 million net gain and $0.2 million of prior-service credit.

• To contribute $6 million to fund significant other postretirement benefit plans during 2024.

• Estimated future benefit payments will be approximately $6 million each year for 2024 through 2028, and $28 million in aggregate for 2029-2033.

13. Share-Based Compensation Plans

The following table summarizes share-based compensation expense recognized in the Consolidated Statements of Income in Compensation and benefits (in millions):

			Years Ended December 31
			2023						2022						2021
Restricted share units			$	283					$	251					$	204
Performance share awards			143						134						189
Employee share purchase plans and other (1)			12						12						56
Total share-based compensation expense			438						397						449
Tax benefit			91						83						87
Share-based compensation expense, net of tax			$	347					$	314					$	362

(1) 2021 includes expenses related to the Aon United Growth Ownership Plan.

Restricted Share Units

RSUs generally vest between three and five years. The fair value of RSUs is based upon the market value of the Company’s class A ordinary shares at the date of grant. With certain limited exceptions, any break in continuous employment will cause the forfeiture of all non-vested awards. Compensation expense associated with RSUs is recognized on a straight-line basis over the requisite service period. Dividend equivalents are paid on certain RSUs, based on the initial grant amount.

The following table summarizes the status of the Company’s RSUs (shares in thousands, except fair value):

			Shares						Fair Value (1)
Non-vested balance at December 31, 2022			2,863						$	238
Granted			1,128						$	302
Vested			(1,124)						$	221
Forfeited			(193)						$	254
Non-vested balance at December 31, 2023			2,674						$	271

(1)Represents per share weighted average fair value of award at date of grant.

The weighted-average grant date fair value of the Company's RSU awards granted during the years ended December 31, 2023, December 31, 2022, and December 31, 2021 was $302, $279, and $253, respectively. The fair value of RSUs that vested during 2023, 2022, and 2021 was $248 million, $216 million, and $189 million, respectively.

Unamortized deferred compensation expense amounted to $477 million as of December 31, 2023, with a remaining weighted average amortization period of approximately 2.0 years.

Performance Share Awards

The vesting of PSAs is contingent upon meeting a cumulative level of adjusted diluted earnings per share related performance over a three-year period. The actual issuance of shares may range from 0-200% of the target number of PSAs granted, based on the terms of the plan and level of achievement of the related performance target. The grant date fair value of PSAs is based upon the market price of the Company’s class A ordinary shares at the date of grant, reduced by the present value of estimated dividends foregone during the vesting period. The performance conditions are not considered in the determination of the grant date fair value for these awards. Compensation expense is recognized over the performance period based on management’s estimate of the number of units expected to vest. Management evaluates its estimate of the actual number of shares expected to be issued at the end of the programs on a quarterly basis. The cumulative effect of the change in estimate is recognized in the period of change as an adjustment to Compensation and benefits in the Consolidated Statements of Income, if necessary. Dividend equivalents are not paid on PSAs.

The following table summarizes the status of the Company's PSAs at 100% of the targeted amount (shares in thousands, except fair value):

			Shares						Fair Value (1)
Non-vested balance at December 31, 2022			1,136						$	222
Granted			331						$	298
Vested			(478)						$	163
Forfeited			(12)						$	285
Non-vested balance at December 31, 2023			977						$	275

(1)Represents per share weighted average fair value of award at date of grant.

The per share weighted-average grant date fair value of the Company's PSA awards granted during the years ended December 31, 2023, December 31, 2022, and December 31, 2021 was $298, $311, and $225, respectively. The payout of shares in 2023 with respect to the PSA awards granted in 2020 based on performance for the three-year performance period ended 2022 was, in aggregate, 956 thousand shares. The fair value of PSAs that vested during 2023, 2022, and 2021 was $156 million, $145 million, and $112 million, respectively.

Unamortized compensation expense, based on current performance levels, amounted to $112 million as of December 31, 2023, with a remaining weighted average amortization period of approximately 1.3 years.

14. Derivatives and Hedging

The Company is exposed to market risks, including changes in foreign currency exchange rates and interest rates. To manage the risk related to these exposures, the Company enters into various derivative instruments that reduce these risks by creating offsetting exposures. The Company does not enter into derivative transactions for trading or speculative purposes.

Foreign Exchange Risk Management

The Company is exposed to foreign exchange risk when it earns revenues, pays expenses, enters into monetary intercompany transfers or other transactions denominated in a currency that differs from its functional currency. The Company uses foreign exchange derivatives, typically forward contracts, options and cross-currency swaps, to reduce its overall exposure to the effects of currency fluctuations on cash flows. These exposures are hedged, on average, for less than two years. These derivatives are accounted for as hedges, and changes in fair value are recorded each period in Other comprehensive income (loss) in the Consolidated Statements of Comprehensive Income.

The Company also uses foreign exchange derivatives, typically forward contracts and options, to economically hedge the currency exposure of the Company’s global liquidity profile, including monetary assets or liabilities that are denominated in a non-functional currency of an entity, typically on a rolling 90-day basis, but may be for up to one year in the future. These derivatives are not accounted for as hedges, and changes in fair value are recorded each period in Other income (expense) in the Consolidated Statements of Income.

The notional and fair values of derivative instruments are as follows (in millions):

			Notional Amount												Net Amount of Derivative Assets Presented in the Statements of Financial Position (1)												Net Amount of Derivative Liabilities Presented in the Statements of Financial Position
As of December 31			2023						2022						2023						2022						2023						2022
Foreign exchange contracts
Accounted for as hedges			$	1,724					$	618					$	34					$	12					$	2					$	2
Not accounted for as hedges (3)			382						312						2						—						1						1
Total			$	2,106					$	930					$	36					$	12					$	3					$	3

(1)Included within Other current assets ($17 million in 2023 and $3 million in 2022) or Other non-current assets ($19 million in 2023 and $9 million in 2022).

(2)Included within Other current liabilities ($3 million in 2023 and $2 million in 2022) or Other non-current liabilities ($1 million in 2022).

(3)These contracts typically are for 90-day durations and executed close to the last day of the most recent reporting month, thereby resulting in nominal fair values at the balance sheet date.

The amounts of derivative gains (losses) recognized in the Consolidated Financial Statements are as follows (in millions):

						2023						2022						2021
(Loss) gain recognized in Accumulated other comprehensive loss						$	8					$	(15)					$	—

The amounts of derivative gains (losses) reclassified from Accumulated other comprehensive loss to the Consolidated Statements of Income are as follows (in millions):

						Years Ended December 31
						2023						2022						2021
Total revenue						$	(8)					$	2					$	(3)
Compensation and benefits						—						—						1
Total						$	(8)					$	2					$	(2)

The Company estimates that approximately $4 million of pretax loss currently included within Accumulated other comprehensive loss will be reclassified into earnings in the next twelve months.

The Company recorded a gain of $37 million in 2023, a gain of $11 million in 2022, and a loss of $24 million in 2021 in Other income (expense) for foreign exchange derivatives not designated or qualifying as hedges.

15. Fair Value Measurements and Financial Instruments

Accounting standards establish a three-tier fair value hierarchy that prioritizes the inputs used in measuring fair values as follows:

• Level 1 — observable inputs such as quoted prices for identical assets in active markets;

• Level 2 — inputs other than quoted prices for identical assets in active markets, that are observable either directly or indirectly; and

• Level 3 — unobservable inputs in which there is little or no market data which requires the use of valuation techniques and the development of assumptions.

The following methods and assumptions are used to estimate the fair values of the Company’s financial instruments, including pension assets (refer to Note 12 “Employee Benefits”):

Money market funds consist of institutional prime, treasury, and government money market funds. The Company reviews treasury and government money market funds to obtain reasonable assurance that the fund net asset value is $1 per share and reviews the floating net asset value of institutional prime money market funds for reasonableness.

Cash and cash equivalents consist of cash and institutional short-term investment funds. The Company reviews the short-term investment funds to obtain reasonable assurance that the fund net asset value is $1 per share.

Equity investments consist of equity securities and equity derivatives valued using the closing stock price on a national securities exchange. Over the counter equity derivatives are valued using observable inputs such as underlying prices of the underlying security and volatility. On a sample basis the Company reviews the listing of Level 1 equity securities in the portfolio, agrees the closing stock prices to a national securities exchange, and independently verifies the observable inputs for Level 2 equity derivatives and securities.

Fixed income investments consist of certain categories of bonds and derivatives. Corporate, government, and agency bonds are valued by pricing vendors who estimate fair value using recently executed transactions and proprietary models based on observable inputs, such as interest rate spreads, yield curves, and credit risk. Asset-backed securities are valued by pricing vendors who estimate fair value using DCF models utilizing observable inputs based on trade and quote activity of securities with similar features. Fixed income derivatives are valued by pricing vendors using observable inputs such as interest rates and yield curves. The Company obtains an understanding of the models, inputs, and assumptions used in developing prices provided by its vendors through discussions with the fund managers. The Company independently verifies the observable inputs, as well as assesses assumptions used for reasonableness based on relevant market conditions and internal Company guidelines. If an assumption is deemed unreasonable, based on internal Company guidelines, it is then reviewed by management and the fair value estimate provided by the vendor is adjusted, if deemed appropriate. These adjustments do not occur frequently and historically are not material to the fair value estimates used in the Consolidated Financial Statements.

Pooled funds consist of various equity, fixed income, and real estate mutual fund type investment vehicles. Pooled investment funds fair value is estimated based on the proportionate share ownership in the underlying net assets of the investment, which is based on the fair value of the underlying securities. The underlying securities typically trade on a national securities exchange or may be valued by the fund managers using applicable models, inputs, and assumptions. The Company gains an understanding of the investment guidelines and valuation policies of the fund and discusses fund performance with pooled fund managers. The Company obtains audited fund manager financial statements, when available. If the pooled fund is designed to replicate a publicly traded index, the Company compares the performance of the fund to the index to assess the reasonableness of the fair value measurement.

Alternative investments consist of limited partnerships, private equity, and hedge funds. Alternative investment fair value is generally estimated based on the proportionate share ownership in the underlying net assets of the investment as determined by the general partner or investment manager. The valuations are based on various factors depending on investment strategy, proprietary models, and specific financial data or projections. The Company obtains audited fund manager financial statements, when available. The Company obtains a detailed understanding of the models, inputs, and assumptions used in developing prices provided by the investment managers, or appropriate party, through regular discussions. The Company also obtains the investment manger’s valuation policies and assesses the assumptions used for reasonableness based on relevant market conditions and internal Company guidelines. If an assumption is deemed unreasonable, based on the Company’s guidelines, it is then reviewed by management and the fair value estimate provided by the vendor is adjusted, if deemed appropriate. These adjustments do not occur frequently and historically are not material to the fair value estimates in the Consolidated Financial Statements.

Derivatives are carried at fair value, based upon industry standard valuation techniques that use, where possible, current market-based or independently sourced pricing inputs, such as interest rates, currency exchange rates, or implied volatility.

Annuity contracts consist of insurance group annuity contracts purchased to match the pension benefit payment stream owed to certain selected plan participant demographics within a few major U.K. defined benefit plans. Annuity contracts are valued using a DCF model utilizing assumptions such as discount rate, mortality, and inflation.

Real estate and REITs consist of publicly traded REITs and direct real estate investments. Level 1 REITs are valued using the closing stock price on a national securities exchange. Non-Level 1 values are based on the proportionate share of ownership in the underlying net asset value as determined by the investment manager. The Company independently reviews the listing of Level 1 REIT securities in the portfolio and agrees the closing stock prices to a national securities exchange. The Company gains an understanding of the investment guidelines and valuation policies of the non-Level 1 real estate funds and discusses performance with the fund managers. The Company obtains audited fund manager financial statements, when available. See the description of “Alternative investments” for further detail on valuation procedures surrounding non-Level 1 REITs.

Debt is carried at outstanding principal balance, less any unamortized issuance costs, discount or premium. Fair value is based on quoted market prices or estimates using DCF analyses based on current borrowing rates for similar types of borrowing arrangements.

The following tables present the categorization of the Company’s assets and liabilities that are measured at fair value on a recurring basis at December 31, 2023 and December 31, 2022 (in millions):

									Fair Value Measurements Using
			Balance at December 31, 2023						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Assets
Money market funds (1)			$	3,204					$	3,204					$	—					$	—
Other investments
Government bonds			$	1					$	—					$	1					$	—
Derivatives (2)
Gross foreign exchange contracts			$	49					$	—					$	49					$	—
Liabilities
Derivatives (2)
Gross foreign exchange contracts			$	16					$	—					$	16					$	—

									Fair Value Measurements Using
			Balance at December 31, 2022						Quoted Prices in Active Markets for Identical Assets (Level 1)						Significant Other Observable Inputs (Level 2)						Significant Unobservable Inputs (Level 3)
Assets
Money market funds (1)			$	3,323					$	3,323					$	—					$	—
Other investments
Government bonds			$	1					$	—					$	1					$	—
Derivatives (2)
Gross foreign exchange contracts			$	19					$	—					$	19					$	—
Liabilities
Derivatives (2)
Gross foreign exchange contracts			$	9					$	—					$	9					$	—

(1)Included within Fiduciary assets or Short-term investments in the Consolidated Statements of Financial Position, depending on their nature and initial maturity.

(2)Refer to Note 14 “Derivatives and Hedging” for additional information regarding the Company’s derivatives and hedging activity.

There were no transfers of assets or liabilities between fair value hierarchy levels during 2023 or 2022. The Company recognized no realized or unrealized gains or losses in the Consolidated Statements of Income related to assets and liabilities measured at fair value using unobservable inputs in 2023, 2022, or 2021.

The fair value of debt is classified as Level 2 of the fair value hierarchy. The following table provides the carrying value and fair value for the Company’s term debt (in millions):

			2023												2022
As of December 31			Carrying Value						Fair Value						Carrying Value						Fair Value
Current portion of long-term debt			$	600					$	595					$	350					$	347
Long-term debt			$	9,995					$	9,223					$	9,825					$	8,745

16. Claims, Lawsuits, and Other Contingencies

Legal

Aon and its subsidiaries are subject to numerous claims, tax assessments, lawsuits, and proceedings that arise in the ordinary course of business, which frequently include E&O claims. The damages claimed in these matters are or may be substantial, including, in many instances, claims for punitive, treble, or extraordinary damages. While Aon maintains meaningful E&O insurance and other insurance programs to provide protection against certain losses that arise in such matters, Aon has exhausted or materially depleted its coverage under some of the policies that protect the Company and, consequently, is self-insured or materially self-insured for some claims. Accruals for these exposures, and related insurance receivables, when applicable, are included in the Consolidated Statements of Financial Position and have been recognized in Other general expense in the Consolidated Statements of Income to the extent that losses are deemed probable and are reasonably estimable. These amounts are adjusted from time to time as developments warrant. Matters that are not probable and reasonably estimable are not accrued for in the financial statements.

The Company’s contingencies and exposures are subject to significant uncertainties, and the determination of likelihood of a loss and estimating any such loss can be complex. The Company is therefore, in certain matters, unable to estimate the range of reasonably possible loss. Although management at present believes that the ultimate outcome of such matters, individually or in the aggregate, will not have a material adverse effect on the consolidated financial position of Aon, legal proceedings are subject to inherent uncertainties and unfavorable rulings or other events. Unfavorable resolutions could include substantial monetary or punitive damages imposed on Aon or its subsidiaries. If unfavorable outcomes of these matters were to occur, future results of operations or cash flows for any particular quarterly or annual period could be materially adversely affected. Certain significant legal proceedings involving us or our subsidiaries are described below.

Current Matters

Aon faces legal action arising out of a fatal plane crash in November 2016. Aon U.K. Limited placed an aviation civil liability reinsurance policy for the Bolivian insurer of the airline. After the crash, the insurer determined that there was no coverage under the airline’s insurance policy due to the airline’s breach of various policy conditions. In November 2018, the owner of the aircraft filed a claim in Bolivia against Aon, the airline, the insurer and the insurance broker. The claim is for $16 million plus any liability the owner has to third parties. In November 2019, a federal prosecutor in Brazil filed a public civil action naming three Aon entities as defendants, along with the airline, the insurer and the lead reinsurer. That claim seeks pecuniary damages for families affected by the crash in the sum of $300 million; or, in the alternative, $50 million; or, in the alternative, $25 million; plus “moral damages” of an equivalent sum. Separately, in March 2020, the Brazilian Federal Senate invited Aon to give evidence to a Parliamentary Commission of Inquiry in an investigation into the accident. Aon cooperated with that inquiry. In August 2020, 43 individuals (surviving passengers and estates of the deceased) filed a motion in the Circuit Court of the 11th Judicial Circuit in and for Miami-Dade County, Florida, seeking permission to commence proceedings against Aon (and the insurer and reinsurers) for claims totaling $844 million. Finally, in April 2021, representatives of 16 passengers issued a claim against Aon in the High Court in England seeking damages under the Fatal Accidents Act 1976 in the sum of £29 million ($36.9 million at December 31, 2023 exchange rates). In December 2022, the High Court in England granted an anti-suit injunction, restricting the 43 individuals who previously filed a motion in the Circuit Court of the 11th Judicial Circuit in and for Miami Dade County, Florida, from continuing litigation in the Circuit Court of the 11th Judicial Circuit against Aon. Aon believes that it has meritorious defenses and intends to vigorously defend itself against the remaining claims.

Certain of the Company’s clients and counterparties have initiated or indicated that they may initiate legal proceedings against the Company following allegations in July 2023 that fraudulent letters of credit were issued in the name of third-party banks in connection with transactions for which capital was arranged by Vesttoo Ltd. (“Vesttoo”). Vesttoo is one of the third parties that identifies capital providers to collateralize insurance and reinsurance obligations of the Company’s clients and counterparties. In certain transactions in which Vesttoo identified third party capital providers to collateralize reinsurance obligations, including transactions in which the Company or its affiliates provided brokerage or other services, some letters of credit from third party banks are alleged to have been fraudulent. The pending or threatened legal proceedings against the Company allege,

among other theories of liability, that in certain circumstances the Company failed to comply with its alleged duty to procure appropriate letters of credit. In particular, on November 30, 2023, Clear Blue Insurance Company and certain of its affiliates filed a lawsuit in New York State Supreme Court against Aon plc and Aon Insurance Managers (Bermuda) Ltd. alleging such claims. While Aon has settled and/or is in discussions to settle certain claims, Aon believes that it has meritorious defenses and intends to vigorously defend itself against those claims that are not settled. In the fourth quarter of 2023, the Company recognized actual or anticipated legal settlement expenses in connection with these matters of $197 million, of which a potentially significant amount may be recoverable in future periods. Aon may also seek recourse against third parties where appropriate, including in connection with bankruptcy proceedings filed by Vesttoo in the Bankruptcy Court for the U.S. District of Delaware. In addition, in August 2023, joint provisional liquidators were appointed over one of the Company’s subsidiaries in Bermuda with respect to segregated accounts that were impacted by the allegedly fraudulent letters of credit. Aon continues to cooperate with regulators in Bermuda, and other regulatory authorities could initiate investigations or proceedings against the Company or third parties.

Guarantees and Indemnifications

The Company provides a variety of guarantees and indemnifications to its customers and others. The maximum potential amount of future payments represents the notional amounts that could become payable under the guarantees and indemnifications if there were a total default by the guaranteed parties, without consideration of possible recoveries under recourse provisions or other methods. These amounts may bear no relationship to the expected future payments, if any, for these guarantees and indemnifications. Any anticipated amounts payable are included in the Consolidated Financial Statements, and are recorded at fair value.

The Company expects that, as prudent business interests dictate, additional guarantees and indemnifications may be issued from time to time.

Guarantee of Registered Securities

On June 22, 2023, Aon plc, Aon Global Limited, Aon Global Holdings plc, Aon Corporation, and Aon North America, Inc., and The Bank of New York Mellon Trust Company, N.A., as trustee (the “Trustee”), as applicable, entered into supplemental indentures, each dated June 22, 2023, amending each of the following indentures (as amended, supplemented or modified from time to time) to add for the benefit of the holders of the instruments issued thereunder a full and unconditional guarantee of Aon North America, Inc. thereunder: (i) Second Amended and Restated Indenture, dated April 1, 2020, among Aon Corporation, Aon plc, Aon Global Limited, Aon Global Holdings plc and the Trustee (amending and restating the Amended and Restated Indenture, dated April 2, 2012, amending and restating the Indenture, dated January 13, 1997); (ii) Second Amended and Restated Indenture, dated April 1, 2020, among Aon Corporation, Aon plc, Aon Global Limited, Aon Global Holdings plc and the Trustee (amending and restating the Amended and Restated Indenture, dated April 2, 2012, amending and restating the Indenture, dated September 10, 2010); (iii) Amended and Restated Indenture, dated April 1, 2020, among Aon plc, Aon Corporation, Aon Global Limited, Aon Global Holdings plc and the Trustee (amending and restating the Indenture, dated December 12, 2012); (iv) Second Amended and Restated Indenture, dated April 1, 2020, among Aon plc, Aon Corporation, Aon Global Limited, Aon Global Holdings plc and the Trustee (amending and restating the Amended and Restated Indenture, dated May 20, 2015, amending and restating the Indenture, dated May 24, 2013); (v) Amended and Restated Indenture, dated April 1, 2020, among Aon plc, Aon Corporation, Aon Global Limited, Aon Global Holdings plc and the Trustee (amending and restating the Indenture, dated November 13, 2015); and (vi) Amended and Restated Indenture, dated April 1, 2020, among Aon Corporation, Aon plc, Aon Global Limited, Aon Global Holdings plc and the Trustee (amending and restating the Indenture, dated December 3, 2018).

Letters of Credit

Aon has entered into a number of arrangements whereby the Company’s performance on certain obligations is guaranteed by a third party through the issuance of LOCs. The Company had total LOCs outstanding of approximately $86 million at December 31, 2023, and $74 million at December 31, 2022. These LOCs cover the beneficiaries related to certain of Aon’s U.S. and Canadian non-qualified pension plan schemes and secure deductible retentions for Aon’s own workers compensation program. The Company has also obtained LOCs to cover contingent payments for taxes and other business obligations to third parties, and other guarantees for miscellaneous purposes at its international subsidiaries.

Premium Payments

The Company has certain contractual contingent guarantees for premium payments owed by clients to certain insurance companies. The maximum exposure with respect to such contractual contingent guarantees was approximately $194 million at December 31, 2023 compared to $173 million at December 31, 2022.

17. Segment Information

The Company operates as one segment that includes all of Aon’s operations, which as a global professional services firm provides a broad range of risk and human capital solutions through four solution lines — Commercial risk, Reinsurance, Health, and Wealth, which make up its principal products and services. The CODM assesses the performance of the Company and allocates resources based on one segment: Aon United.

The Company’s reportable operating segment has been determined using a management approach, which is consistent with the basis and manner in which the CODM uses financial information for the purposes of allocating resources and evaluating performance. The CODM assesses performance and allocates resources based on total Aon results against its key four metrics, expense discipline, and collaborative behaviors that maximize value for Aon and its shareholders, regardless of which solution line it benefits.

As Aon operates as one segment, segment profit or loss is consistent with consolidated reporting as disclosed in the Consolidated Statements of Income. Refer to Note 3 “Revenue from Contracts with Customers” for further information on revenue by principal service line.

Consolidated long-lived assets, net by geographic area are as follows (in millions):

As of December 31			Total						United States						Americas other than U.S.						United Kingdom						Ireland						Other Europe, Middle East, & Africa						Asia Pacific
2023			$	1,314					$	492					$	124					$	159					$	7					$	297					$	235
2022			$	1,300					$	519					$	120					$	155					$	9					$	279					$	218