UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

Commission file number: 1-7933

Aon plc

(Exact name of registrant as specified in its charter)

Metropolitan Building, James Joyce Street, Dublin 1, Ireland D01 K0Y8

(Address of principal executive offices) (Zip Code)

+353 1 266 6000

(Registrant’s Telephone Number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

S****ecurities registered pursuant to Section 12(g) of the Act: NONE

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☒ No ☐

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Exchange Act. Yes ☐ No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☒

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

As of June 30, 2022, the aggregate market value of the registrant’s Class A Ordinary Shares held by non-affiliates of the registrant was $57,066,496,679 based on the closing sales price as reported on the New York Stock Exchange — Composite Transaction Listing.

Number of the registrant’s Class A Ordinary Shares of Aon plc, $0.01 nominal value, outstanding as of February 16, 2023: 205,142,379.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s proxy statement for its 2023 Annual General Meeting of Shareholders are incorporated by reference in this report in response to Part III, Items 10, 11, 12, 13, and 14.

Information Concerning Forward-Looking Statements

This report contains certain statements related to future results, or states our intentions, beliefs, and expectations or predictions for the future, all of which are forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995. Forward-looking statements represent management’s expectations or forecasts of future events. Forward-looking statements are typically identified by words such as “anticipate,” “believe,” “estimate,” “expect,” “forecast,” “project,” “intend,” “plan,” “probably,” “potential,” “looking forward,” “continue,” and other similar terms, and future or conditional tense verbs like “could,” “may,” “might,” “should,” “will,” and “would.” You can also identify forward-looking statements by the fact that they do not relate strictly to historical or current facts. For example, we may use forward-looking statements when addressing topics such as: market and industry conditions, including competitive and pricing trends; changes in our business strategies and methods of generating revenue; the development and performance of our services and products; changes in the composition or level of our revenues; our cost structure and the outcome of cost-saving or restructuring initiatives; the outcome of contingencies; dividend policy; the expected impact of acquisitions, dispositions, and other significant transactions or the termination thereof; litigation and regulatory matters; pension obligations; cash flow and liquidity; expected effective tax rate; expected foreign currency translation impacts; potential changes in laws or future actions by regulators; and the impact of changes in accounting rules. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from either historical or anticipated results depending on a variety of factors. Potential factors, which may be revised or supplemented in subsequent reports filed or furnished with the Securities and Exchange Commission, that could impact results include:

• changes in the competitive environment, due to macroeconomic conditions or otherwise, or damage to our reputation;

• fluctuations in currency exchange, interest, or inflation rates that could impact our financial condition or results;

• changes in global equity and fixed income markets that could affect the return on invested assets;

• changes in the funded status of our various defined benefit pension plans and the impact of any increased pension funding resulting from those changes;

• the level of our debt and the terms thereof reducing our flexibility or increasing borrowing costs;

• rating agency actions that could limit our access to capital and our competitive position;

• our global tax rate being subject to a variety of different factors, including the adoption and implementation in the European Union, the United States, the United Kingdom, or other countries of the Organization for Economic Co-operation and Development tax proposals or other pending proposals in those and other countries, which could create volatility in that tax rate;

• changes in our accounting estimates and assumptions on our financial statements;

• limits on our subsidiaries’ ability to pay dividends or otherwise make payments to us;

• the impact of legal proceedings and other contingencies, including those arising from acquisition or disposition transactions, errors and omissions and other claims against us;

• the impact of, and potential challenges in complying with, laws and regulations of the jurisdictions in which we operate, particularly given the global nature of operations and the possibility of differing or conflicting laws and regulations, or the application or interpretation thereof, across such jurisdictions;

• the impact of any regulatory investigations brought in Ireland, the United Kingdom, the United States, and other countries;

• failure to protect intellectual property rights or allegations that we have infringed on the intellectual property rights of others;

• general economic and political conditions in the countries in which we do business around the world;

• the failure to retain, attract and develop experienced and qualified personnel;

• international risks associated with our global operations, including impacts from military conflicts or political instability, such as the ongoing Russian war in Ukraine;

• the effects of natural or man-made disasters, including the effects of the COVID-19 pandemic and other health pandemics and the impacts of climate change;

• any system or network disruption or breach resulting in operational interruption or improper disclosure of confidential, personal, or proprietary data, and resulting liabilities or damage to our reputation;

• our ability to develop, implement, update, and enhance new technology;

• the actions taken by third parties that perform aspects of our business operations and client services;

• the extent to which we are exposed to certain risks, including lawsuits, related to our actions we may take in being responsible for making decisions on behalf of clients in our investment businesses or in other advisory services that we currently provide, or will provide in the future;

• our ability to continue, and the costs and risks associated with growing, developing and integrating acquired business, and entering into new lines of business or products;

• our ability to secure regulatory approval and complete transactions, and the costs and risks associated with the failure to consummate proposed transactions;

• changes in commercial property and casualty markets, commercial premium rates or methods of compensation;

• our ability to develop and implement innovative growth strategies and initiatives intended to yield cost savings, and the ability to achieve such growth or cost savings; and

• the effects of Irish law on our operating flexibility and the enforcement of judgments against us.

Any or all of our forward-looking statements may turn out to be inaccurate, and there are no guarantees about our performance. The factors identified above are not exhaustive. Aon and its subsidiaries operate in a dynamic business environment in which new risks may emerge frequently. Accordingly, readers should not place undue reliance on forward-looking statements, which speak only as of the dates on which they are made. We are under no (and expressly disclaim any) obligation to update or alter any forward-looking statement that we may make from time to time, whether as a result of new information, future events, or otherwise. Further information about factors that could materially affect Aon, including our results of operations and financial condition, is contained in the “Risk Factors” section in Part I, Item 1A of this report.

Table of Contents

The below definitions apply throughout this report unless the context requires otherwise:

PART I

OVERVIEW

Aon plc (which may be referred to as “Aon,” the “Company,” “we,” “us,” or “our”) is a leading global professional services firm providing a broad range of risk, health, and wealth solutions. Through our experience, global reach, and comprehensive analytics, we are better able to help clients meet rapidly changing, increasingly complex, and interconnected challenges. We are committed to accelerating innovation to address unmet and evolving client needs, so that our clients are better informed, better advised, and able to make better decisions to protect and grow their business. Management is focused on strengthening Aon and uniting the firm with one portfolio of capability enabled by data and analytics and one operating model to deliver additional insight, connectivity, and efficiency.

Our clients are in over 120 countries and sovereignties and include all market segments and almost every industry. This diversification of our customer base helps provide us stability in different economic scenarios that could affect specific industries, customer segments, or geographies.

We have continued to focus our portfolio on higher-margin, capital-light professional services businesses that have high recurring revenue streams and strong cash flow generation. We endeavor to make capital allocation decisions based upon return on invested capital.

BUSINESS SEGMENT

The Company operates as one segment that includes all of Aon’s continuing operations, which, as a global professional services firm, provides advice and solutions to clients focused on risk, health and wealth through four principal products and services: Commercial Risk Solutions, Reinsurance Solutions, Health Solutions, and Wealth Solutions. Collectively, these products and service lines make up our one segment: Aon United. In addition, the Company is continuing to expand on Aon United growth initiatives through its Aon Growth Ventures Group.

In 2022, our consolidated total revenue was $12,479 million. This includes $6,715 million in Commercial Risk Solutions, $2,190 million in Reinsurance Solutions, $2,224 million in Health Solutions, and $1,367 million in Wealth Solutions, before certain intercompany eliminations.

Principal Products and Services

Commercial Risk Solutions includes retail brokerage, specialty solutions, global risk consulting and captives management, and Affinity programs. In retail brokerage, our dedicated teams of risk professionals utilize comprehensive analytics capabilities and insights providing clients with risk advice for their organizations. We utilize Aon’s differentiated capabilities in industry sector- and segment-specific approaches, like Digital Client Solutions, to risk transfer options and deliver them through a variety of channels including bespoke solutions for complex needs, structured solutions for mid-market and small and medium-sized enterprises, and digital distribution including CoverWallet. Our specialty-focused organizational structure includes financial and professional lines, cyber, surety and trade credit, crisis management, transaction liability, climate, and intellectual property. We develop market leading insights on the most efficient risk transfer vehicles for clients in today’s complex and integrated risk environment to enable clients to make better decisions. Global risk consulting and captive management is a global leader in supporting better management of companies’ risk profiles by identifying and quantifying the risks they face, mapping out optimal risk mitigation, retention and transfer solutions and thus enabling them to be more informed to make better decisions for their businesses. Affinity programs include development, marketing, and administration of customized and targeted insurance programs, facilities, and other structured solutions, including Aon Client Treaty. We collaborate with sponsors and other privileged distribution channels through which Aon can deliver differentiated, highly targeted, and highly valuable solutions for unique risk solutions.

Reinsurance Solutions includes treaty reinsurance, facultative reinsurance, Strategy and Technology Group and capital markets. Treaty reinsurance addresses underwriting and capital objectives on a portfolio level, allowing our clients to more effectively manage the combination of premium growth, return on capital, and rating agency interests on an integrated basis. This includes the development of more competitive, innovative, and efficient risk transfer options. Facultative reinsurance empowers clients to better understand, manage, and transfer risk through innovative facultative solutions and provides the most efficient access to the global facultative reinsurance markets. Strategy and Technology Group combines strategic advice with data-driven consulting, analytics, and modeling tools, including Tyche, ReMetrica, and PathWise, to help clients deploy capital efficiently and effectively. We develop highly customized solutions that help clients drive growth and operational efficiency, improve balance sheet strength and resiliency, and comply with regulatory and operational requirements, including through the execution of reinsurance transactions. Capital markets is a global investment bank with expertise in insurance-linked securities,

capital raising, strategic advice, restructuring, and mergers and acquisitions. We partner with insurers, reinsurers, investment firms, and corporations in executing innovative risk management products, capital market solutions and corporate finance advisory services.

Health Solutions includes consulting and brokerage, consumer benefits solutions, and human capital solutions. Consulting and brokerage develops and implements innovative, customized health and benefits strategies for clients of all sizes across industries and geographies to manage risk, drive engagement, and strengthen the workforce through improved health and wellbeing. We partner with insurers and other strategic partners to develop and implement new and innovative solutions and leverage world-class analytics and technology to help clients make informed decisions and manage healthcare outcomes. Consulting and brokerage also advises multinational companies on global benefits, including insurance placement across more than 120 countries and sovereignties, program design and management, financing optimization, and enhanced employee experience, as well as assists in navigating global regulatory and compliance requirements in countries in which they operate. Consumer benefits solutions designs and delivers innovative voluntary consumer benefits that improve an employer’s total rewards strategy and positively impacts their employees’ financial and overall wellbeing. We leverage our proprietary digital platform to provide efficient enrollment strategies through an effective combination of data, analytics, and tailored products. Multi-channel and targeted communications solutions increase consumer benefit knowledge and enhance engagement. Our human capital team delivers data, analytics, and advice to business leaders so they can make better workforce decisions and align their business and people strategies. We support clients across the full employee lifecycle, including talent assessment and selection, compensation benchmarking, total rewards strategy optimization, workforce analytics and benchmarking, workforce resilience planning, human capital integration in transaction situations, Corporate Governance, ESG consulting, and strategic employee communication.

Wealth Solutions includes retirement consulting, pension administration, and investments consulting. Retirement consulting specializes in providing clients across the globe with strategic design consulting on their retirement programs, actuarial services, and risk management, including pension de-risking, governance, integrated pension administration and legal and compliance consulting. We also help organizations manage their balance sheet volatility. Retirement consulting and pension administration leverage Aon’s pension expertise to deliver high-quality integrated retirement services. Our customized services include outsourcing, co-sourcing and in-sourcing options. Our partnership-driven model is powered by deep pension experience and enabled with smart technology. Our investments consulting team provides public and private companies and other institutions with advice on developing and maintaining investment programs across a broad range of plan types, including defined benefit plans, defined contribution plans, endowments and foundations. Our delegated investment solutions offer ongoing management of investment programs and fiduciary responsibilities either in a partial or full discretionary model for multiple asset owners. We partner with clients to deliver our scale and experience to help them effectively manage their investments, risk, and governance and potentially lower costs. We believe in the power of connecting participants to experts to make better informed and smarter decisions about their wealth.

Revenue and Compensation

Our business generates revenues primarily through commissions, compensation from insurance and reinsurance companies for services we provide 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 we act. 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 and reinsurers. Fees from clients for advice and consulting services are dependent on the extent and value of the services we provide. Payment terms are consistent with current industry practices.

Funds Held on Behalf of Clients

We typically hold funds on behalf of clients, including premiums received from clients and claims due to clients that are in transit to and from insurers. Certain funds held on behalf of clients are invested in interest-bearing premium trust accounts and can fluctuate significantly depending on when we collect and remit cash. The principal is segregated and not available for general operating purposes, although we may earn interest on these accounts.

Competition

Our business operates in a highly competitive and fragmented environment. We compete with numerous other global insurance brokers and consulting companies, including, among others, Marsh & McLennan Companies, Inc., Willis Towers Watson Public Limited Company, Arthur J Gallagher & Company, Lockton Companies, Inc., as well as numerous other global, regional, and local firms in almost every area of our business. We also compete with insurance and reinsurance companies that directly market and service their insurance products without the assistance of brokers or agents. Additionally, we compete with

other businesses that do not fall into the categories above, including large financial institutions and independent consulting firms and consulting organizations affiliated with accounting, information systems, technology, and financial services firms.

Seasonality

Due to buying patterns and delivery of certain products and services in the markets we serve, revenues recognized tend to be higher in the first and fourth quarters of each fiscal year.

Licensing and Regulation

Our business activities are subject to licensing requirements and extensive regulation under the laws of countries in which we operate, including U.S. federal and state laws. See the “Risk Factors” section in Part I, Item 1A of this report for information regarding how actions by regulatory authorities or changes in legislation and regulation in the jurisdictions in which we operate may have an adverse effect on our business.

Regulatory authorities in the U.S. and most other countries in which our operating subsidiaries conduct business may require individuals, entities, and related service providers to obtain a license from a government agency, including (but not limited to) licenses to operate as insurance producers, brokers, agents, consultants, reinsurance brokers, or managing general agents.

Certain jurisdictions issue licenses only to resident entities or individuals. In such jurisdictions, if the Company has no licensed subsidiary, we may maintain arrangements with residents or business entities licensed to act in such jurisdiction. Such arrangements are subject to an internal review and approval process.

Our subsidiaries must comply with laws and regulations of the jurisdictions in which they do business. These laws and regulations are enforced by the FCA in the U.K., by federal and state agencies in the U.S., and by various regulatory agencies and other supervisory authorities in other countries through the granting and revoking of licenses to do business, the licensing of agents, the monitoring of trade practices, policy form approval, limits on commission rates, and mandatory remuneration disclosure requirements.

Insurance authorities in the U.K., U.S., and certain other jurisdictions in which our subsidiaries operate have enacted laws and regulations governing the investment of funds, such as premiums and claims proceeds, held in a fiduciary capacity for others. These laws and regulations generally require the segregation of these fiduciary funds and limit the types of investments that may be made with them.

Investment, securities, and futures licensing authorities also govern certain business activities. For example, in the U.S., we use Aon Securities LLC, an indirect, wholly owned subsidiary of Aon, and a U.S.-registered broker-dealer and investment advisor, member of FINRA and Securities Investor Protection Corporation, for investment banking, capital advisory services and other broker-dealer activities. Similar operations exist in other jurisdictions outside of the U.S.

Further, pension and financial laws and regulations, including oversight and supervision by the FCA in the U.K., the SEC and the DOL in the U.S., and regulators in other countries govern certain of the retirement-related consulting services provided by Aon and its subsidiaries and affiliates. This includes Aon subsidiaries that provide investment advisory services regulated by various U.S. federal authorities including the SEC, DOL, and FINRA, as well as authorities on the state level. In addition, other services provided by Aon and its subsidiaries and affiliates, such as trustee services and retirement and employee benefit program administrative services, are subject in various jurisdictions to pension, investment, securities, and insurance laws and regulations, and supervision.

Clientele

Our clients operate in many businesses and industries throughout the world. No one client accounted for more than 2% of our consolidated total revenues in 2022. Additionally, we place insurance with many insurance carriers, none of which individually accounted for more than 10% of the total premiums we placed on behalf of our clients in 2022.

Aon United, Our Culture, and Human Capital Strategy

Our Culture

Our culture is driven by our values – committed as one firm to our purpose, united through trust as one inclusive, diverse team, and passionate about making our colleagues and clients successful. Our colleagues are the cornerstone of Aon's success. Collaboration and innovation drive our culture, bringing the best of Aon to clients in a holistic and seamless manner. Our Aon United strategy defines how Aon colleagues work together to deliver value to clients, setting a new standard for client leadership. Aon United is brought to life through our common client value creation model which scales strategies from across

the firm to bring the best of Aon to clients. Each year, Aon makes significant philanthropic contributions to various organizations, supports numerous colleague volunteer opportunities, and offers paid time off to volunteer.

Colleagues

As of December 31, 2022, we employed approximately 50,000 employees and conducted our operations in more than 120 countries and sovereignties. Our colleagues’ diverse talents, expertise, and insights contribute to the success of both our firm and our clients, and we seek to attract, grow, and retain the best talent in the industry. Our Inclusive People Leadership strategy is a central part of our Aon United Blueprint and is a key enabler to realizing our aspirations and purpose as a firm. At Aon, all colleagues are called upon to be leaders in embracing and modelling our Aon United values and behaviors. Inclusive People Leadership at Aon ensures that all colleagues – at every stage of their career journey – are equipped and motivated to deliver on our purpose and able to achieve their full potential. Colleagues benefit from our “Smart Working” approach. The aim of Smart Working is to create a healthy, productive, inclusive, and sustainable way of working, enabling colleagues to deliver their best work for clients from wherever they are best placed to do so. This strategy, which supports in person, hybrid, and virtual working, continues to be a source of positive feedback and strong engagement based on colleague surveys.

Training and Development

We invest significant resources to develop the talent needed to remain at the forefront of innovation and remain an attractive employer. Colleagues are invited to complete a variety of curricula to meet their career stage goals and developmental needs. We provide our colleagues what they need to learn, grow, and become the leaders our clients seek. From self-guided learning courses to advanced leadership programs, the curriculum is aligned to the Aon United Blueprint and Inclusive People Leader strategy. Aon’s investment in technology and use of virtual based learning and development programs allows us to deliver targeted offerings designed to advance all colleagues’ development.

Colleague Engagement and Retention

Providing an engaging and rewarding colleague experience is a top priority for our firm and understanding colleagues’ feedback helps us reach that goal. We use a variety of channels to facilitate open, on-going, and direct communication with colleagues. These channels include open forums and town halls with executives, colleague surveys, and engagement through our Business Resource Groups. Business Resource Groups are our independent, voluntary, non-profit associations that provide input, take action, and help identify opportunities for our firm to further commitments to I&D and belonging.

Our engagement survey process consists of frequent pulse surveys, as well as our annual all colleague support survey which enables us to understand how colleagues are engaging with their teams, the firm, and clients. This outreach effort allows us to gather insights more rapidly, take timely action to address feedback, and deliver on the needs of colleagues in real time – ensuring colleagues feel more connected, more valued and more relevant. The pulse surveys for 2022 were focused on topics such as manager and leadership support, delivering on our Aon Story, colleague wellbeing, I&D, talent acquisition and performance & rewards. Aon’s feedback from our workforce provides management a better understanding of evolving colleague viewpoints, and ensures we are taking appropriate steps to drive colleague engagement and retention. For discussion of the risks related to the attraction and retention of senior management and other professional personnel, see the “Risk Factors” section in Part I, Item 1A of this report.

Rewards

In addition to an inspired purpose and culture, we are proud to offer our colleagues a total rewards program that combines competitive pay, incentive opportunities, and benefits. Our compensation programs, including salary, recognition, cash, and equity incentives, are connected to our formal performance management, and career development approach. These programs serve to reward colleagues for their Aon United impact both in what they accomplish for clients, colleagues, and shareholders, how they achieve those results and how they deliver on our values. We maintain a global commitment to colleague wellbeing and play a key role in supporting colleagues across the physical, emotional, financial, and social spectrum. Our comprehensive benefit programs are competitive for the markets in which we operate and aligned with our values and culture. Eligible colleagues that were active on September 24, 2021 received a one-time stock based award enabling Aon colleagues to share in the future success of our Aon United mission.

Our compensation philosophy aligns with our Aon United strategy and delivering long-term shareholder value creation. Our executive incentives are based on driving results, delivery of strategic initiatives, and leadership. Beginning in 2021, 20% of the short-term incentives for senior executives are based on quantifiable performance against firm-wide I&D initiatives.

Inclusion and Diversity

We believe that inclusive and diverse teams produce better insight, better solutions, and ultimately the best outcomes for clients and Aon’s long-term success.

We are focused on being a firm that is representative of the communities in which we operate. We achieve this by aligning I&D actions to the following pillars: Recruitment, Education, Promotion, and Representation. We strongly believe that only when colleagues can be their authentic selves will they reach their full potential.

Our commitment to I&D starts from the top with our Board of Directors, including its I&D Sub-Committee. Our Global Inclusive Leadership Council is sponsored by our Chief Executive Officer and Chief People Officer. Regional Inclusive Leadership Councils and our Executive Leadership Teams are aligned to drive actions to increase the diversity of our teams. Our colleague-led Business Resource Groups also support execution and provide additional opportunities for colleagues to enhance our inclusive environment.

As of December 31, 2022, Aon’s global workforce was 54% women and 46% men, and the Aon Executive Committee which leads the firm was 48% women and 52% men. At the manager level, 28% of senior leaders and 43% of managers with one or more direct report were women. New colleague hires for the year were 51% women and 49% men. Aon’s U.S. workforce was 25% racially or ethnically diverse, calculated as a percentage of colleagues that have voluntarily disclosed their race or ethnicity to Aon. At the manager level, 13% of U.S. senior leaders and 18% of U.S. managers with one or more direct report were racially or ethnically diverse. New colleague hires for the year in the U.S. were 31% racially or ethnically diverse.

Our Apprenticeship Program

Apprenticeship programs help build a talent pipeline of highly skilled and diverse professionals while providing apprentices with advanced education and work experience. By removing some of the traditional barriers to entry-level employment, Aon can contribute to local workforce development and cultivate talent while improving retention rates in these entry-level roles. As a founding member of seven apprentice networks within the U.S., we partner with companies and organizations to assist them in building their own programs through sharing best practices and learnings. Across these networks, we have over 160 organizations committed as of December 31, 2022.

Aon's two-year Apprenticeship Program, which was implemented in the U.K. and U.S. in 2012 and 2017, respectively, serves as an alternate route into a permanent role that normally requires a specific degree or professional experience. Aon provides motivated, high-potential individuals with the required training (on the job and in the classroom), professional skills development, mentorship, and experiential learning to bridge the gap. Over 585 Aon apprentices have been hired since the inception of the program across the U.S. and U.K. Both programs are certified apprenticeship programs, by the Department of Labor in the U.S. and the Department of Education in the U.K.

Website Access to Reports and Other Information

Our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, and all amendments to those reports are made available free of charge through our website (http://www.aon.com) as soon as reasonably practicable after such material is electronically filed with or furnished to the SEC. Also posted on our website are the charters for our Audit, Organization and Compensation, Governance/Nominating, and Finance Committees, and Compliance and Inclusion & Diversity Sub-Committees, our Governance Guidelines, and our Code of Business Conduct. Within the time period required by the SEC and the NYSE, we will post on our website any amendment to or waiver of the Code of Business Conduct applicable to any executive officer or director. In addition, we may announce material information to investors and the marketplace using our investor relations website. While not all of the information that we post to such website is of a material nature, some information could be deemed to be material. Accordingly, we encourage investors, the media, and others interested in our company to review the information that we share at our investor relations link located at the bottom of the page on www.aon.com. The information provided on our website is not part of this report and is therefore not incorporated herein by reference.

The risk factors set forth below reflect risks associated with our existing and potential businesses and the industries in which we operate generally and contain “forward-looking statements” as discussed in the “Business” Section of Part I, Item 1 of this report. Readers should consider these risks in addition to the other information contained in this report because our business, financial condition, or results of operations could be materially adversely affected if any of these risks were to actually occur and the occurrence of such risks could cause our actual results to differ materially from those stated in or implied by the forward-looking statements in this document and elsewhere.

Risks Related to Our Business

An overall decline in economic and business activity could have a material adverse effect on the financial condition and results of operations of our business.

The results of our operations are generally affected by the level of business activity of our clients, which in turn is affected by the economy of the industries and markets these clients serve. Economic downturns, volatility, or uncertainty in the broader economy or in specific markets (including as a result of endemics or pandemics, climate change, political unrest, actions by central banks, or otherwise) may cause reductions in technology and discretionary spending by our clients, which may result in reductions in the growth of new business or reductions in existing business. If our clients become financially less stable, enter bankruptcy, liquidate their operations or consolidate, our revenues and collectability of receivables could be adversely affected.

The demand for property and casualty insurance generally rises as the overall level of economic activity increases and generally falls as such activity decreases, affecting both the commissions and fees generated by our Commercial Risk Solutions and Reinsurance Solutions lines. The economic activity that impacts property and casualty insurance is most closely correlated with employment levels, corporate revenues, and asset values. Downward fluctuations in the year-over-year insurance premiums charged by insurers to protect against the same risk, referred to in the industry as softening of the insurance market, could adversely affect these businesses as a significant portion of the revenue is determined as a percentage of premiums charged to our clients. In addition, certain discretionary services within our business, such as Human Capital, project-related work within Commercial Risk Solutions and Health Solutions, and transaction liability, may see a decrease in activity if the overall level of economic activity results in a reduction to our clients’ discretionary spending. Insolvencies and consolidations associated with an economic downturn, especially insolvencies in the insurance industry, could adversely affect our brokerage business through the loss of clients by hampering our ability to place insurance and reinsurance business. Also, error and omission claims against us, which we refer to as E&O claims, may increase in economic downturns, also adversely affecting our business. In addition, decreased underwriting capacity for insurance and reinsurance may create difficulty for our professionals to place business, which may adversely impact our ability to earn revenue.

We face significant competitive pressures from traditional and non-traditional competitors that could affect our business.

As a global professional services firm, we compete with global, national, regional, and local insurance companies that market and service their own products, other financial services providers, brokers, and investment managers, independent firms, and consulting organizations affiliated with accounting, information systems, technology, human resources consulting, and financial services firms. We compete with respect to service, delivery of insights, product features, price, commission structure, technology, financial strength, ability to access certain insurance markets, and name recognition. Our competitors may have better financial, technical and marketing resources, broader customer bases, greater name recognition, more comprehensive products, stronger presence in certain geographies, or more established relationships with their customers and suppliers than we have.

Alliances or mergers among competitors could affect our business. Further, we compete on pricing and the innovation and quality of our service offerings and could be affected by competitors’ lower cost structures, product development activities, and pricing policies, any or all of which could result in better market acceptance of our competitors’ offerings than those that we offer or develop.

This competition is further intensified by an industry trend where clients elect to engage multiple brokers to service different portions of their accounts. If we fail to respond successfully to the evolving competition we face, our financial condition or results of operations might be adversely affected.

If we are unable to effectively develop and implement innovative strategies, efficiencies and new solutions for our clients, our reputation, ability to compete effectively and financial condition may be adversely affected.

Developing and implementing innovative strategies, efficient business practices, and new solutions to current and emerging client needs is important to our business. We may be unsuccessful in developing innovative strategies, or our competitors may be more successful in innovating and delivering services to meet new and existing client needs. Competitors may be able to innovate faster and respond better to evolving client demand and industry conditions, or price their services more aggressively than we do. Further, new and non- traditional competitors, our clients’ increasing ability and determination to self-insure, and capital market alternatives to traditional insurance and reinsurance markets cause additional forms of competition and innovation that could affect our business. If we are unsuccessful in innovating, if we cannot innovate as quickly as our competitors, if we are not able to make sufficient investment in innovation, if our competitors develop more cost-effective technologies, or if our ideas are not accepted in the marketplace, it could have a material adverse effect on our ability to obtain and complete client engagements.

For example, we have invested significantly in the development of our proprietary data and analytics tools including repositories of global insurance and reinsurance placement information, which we use to drive results for our clients in the insurance and reinsurance placement process. Our competitors have or are developing competing data and analytics tools, and their success in this space may impact our ability to differentiate our services to our clients through the use of unique technological solutions. Innovations in software, cloud computing, data and analytics or other technologies that alter how our services are delivered could significantly undermine our investment in the business if we are slow to innovate or unable to take advantage of these developments.

In addition, innovation in technology, capabilities, and the entry into new lines of business, services, or products require significant investment and present additional risks to the Company, particularly in instances where the markets are new or not fully developed. Such risks include the investment of significant time and resources; the possibility that these efforts will not be successful and could result in reputational damage to us; the possibility that the marketplace does not accept our products or services or that we are unable to retain clients that adopt our new products or services; and the risk of new or additional liabilities associated with these efforts, including potential E&O or other claims.

**If our clients are not sa

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None.

We have offices in various locations throughout the world. Substantially all of our offices are located in leased premises. We maintain our corporate headquarters at Metropolitan Building, James Joyce Street, Dublin 1, Ireland, where we occupy approximately 43,000 square feet of space under an operating lease agreement that expires in 2032. The following are additional significant leased properties, along with the occupied square footage and expiration.

As leases expire, we do not anticipate difficulty in negotiating renewals or finding other satisfactory space if the premise becomes unavailable. We believe that the facilities we currently occupy are adequate for the purposes for which they are being used and are well maintained. In certain circumstances, we may have unused space and may seek to sublet such space to third parties, depending upon the demands for office space in the locations involved. See Note 8 “Lease Commitments” of the Notes

to Consolidated Financial Statements in Part II, Item 8 of this report for information with respect to our lease commitments as of December 31, 2022.

We hereby incorporate by reference Note 15 “Claims, Lawsuits, and Other Contingencies” of the Notes to Consolidated Financial Statements in Part II, Item 8 of this report.

Not applicable.

Information about our Executive Officers

The executive officers of Aon, as of February 17, 2023 unless otherwise noted, their business experience during a period of the last five years or longer, and their ages and positions held are set forth below.

PART II

Our class A ordinary shares, $0.01 nominal value per share, are traded on the NYSE under the trading symbol AON.

On February 16, 2023, the last reported sale price of our ordinary shares as reported by the NYSE was $310.25 per share. We have approximately 409 holders of record of our class A ordinary shares as of February 16, 2023.

The following information relates to the repurchases of equity securities by Aon or any affiliated purchaser during each month within the fourth quarter of the fiscal year covered by this report:

(1)Does not include commissions paid to repurchase shares.

(2)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.

Information relating to the compensation plans under which equity securities of Aon are authorized for issuance is set forth under Part III, Item 12 “Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters” of this report and is incorporated herein by reference.

We did not make any unregistered sales of equity in 2022.

EXECUTIVE SUMMARY OF 2022 FINANCIAL RESULTS

Aon plc is a leading global professional services firm providing a broad range of risk, health, and wealth solutions. Through our experience, global reach, and comprehensive analytics, we are better able to help clients meet rapidly changing, increasingly complex, and interconnected challenges. We are committed to accelerating innovation to address unmet and evolving client needs, so that our clients are better informed, better advised, and able to make better decisions to protect and grow their business. Management is focused on strengthening Aon and uniting the firm with one portfolio of capability enabled by data and analytics and one operating model to deliver additional insight, connectivity, and efficiency.

Financial Results

The following is a summary of our 2022 financial results:

• Revenue increased $286 million, or 2%, to $12.5 billion in 2022 compared to 2021, reflecting 6% organic revenue growth and a 1% favorable impact from fiduciary investment income, partially offset by a 4% unfavorable impact from foreign currency translation a 1% unfavorable impact from acquisitions, divestitures and other.

• Operating expenses decreased $1.3 billion, or 13%, to $8.8 billion in 2022 compared to 2021 due primarily to the $1.0 billion payment made in connection with terminating the combination with WTW (the “Termination Fee”) and certain transaction costs incurred related to the termination in the prior year (together, the “Transaction Costs”) and a $373 million favorable impact from foreign currency translation, partially offset by an increase in expense associated with 6% organic revenue growth, investments in long-term growth, and a $58 million charge related to certain legal settlements reached.

• Operating margin increased to 29.4% in 2022 from 17.1% in 2021. The increase was driven by a decrease in operating expenses as listed above and organic revenue growth of 6%.

• Due to the factors set forth above, Net income was $2.6 billion in 2022, an increase of $1.3 billion, or 102%, from 2021.

• Diluted earnings per share increased 119% to $12.14 per share during the twelve months of 2022 compared to $5.55 per share for the prior year period.

• Cash flows provided by operating activities was $3.2 billion in 2022, an increase of $1.0 billion, or 48%, from $2.2 billion in 2021, primarily due to the Transaction Costs paid in the prior year period, and strong operating income growth, partially offset by higher incentive compensation payments made in the current year following strong performance in 2021.

We focus on four key metrics not presented in accordance with U.S. GAAP that we communicate to shareholders: organic revenue growth, adjusted operating margin, adjusted diluted earnings per share, and free cash flow. These non-GAAP metrics should be viewed in addition to, not instead of, our Consolidated Financial Statements. The following is our measure of performance against these four metrics for 2022:

• Organic revenue growth, a non-GAAP measure defined under the caption “Review of Consolidated Results — Organic Revenue Growth,” was 6% in 2022, compared to 9% organic growth in the prior year.

• Adjusted operating margin, a non-GAAP measure defined under the caption “Review of Consolidated Results — Adjusted Operating Margin,” was 30.8% in 2022, compared to 30.1% in the prior year. The increase in adjusted operating margin primarily reflects 6% organic revenue growth and a higher fiduciary investment income, partially offset by increased expenses and investments in long-term growth.

• Adjusted diluted earnings per share, a non-GAAP measure defined under the caption “Review of Consolidated Results — Adjusted Diluted Earnings per Share,” was $13.39 per share in 2022, an increase of $1.39 per share, or 12%, from $12.00 per share in 2021. The increase in adjusted diluted earnings per share primarily reflects strong operational performance and effective capital management, highlighted by $3.2 billion of share repurchase during 2022, partially offset by an unfavorable impact from foreign currency translation.

• Free cash flow, a non-GAAP measure defined under the caption “Review of Consolidated Results — Free Cash Flow,” was $3.0 billion in 2022, an increase of $978 million, or 48%, from $2.0 billion in 2021, reflecting an increase in Cash flows from operations, partially offset by a $59 million increase in capital expenditures.

ENVIRONMENTAL, SOCIAL, AND GOVERNANCE

For many companies, the management of ESG risks and opportunities has become increasingly important, and ESG-related challenges, such as extreme weather events, supply chain disruptions, cyber events, regulatory changes, ongoing public health impacts, and the increased focus on workforce resilience in highly varied work environments continue to create volatility and uncertainty for our clients. Aon offers a wide range of risk assessment, consulting and advisory solutions, many of which are significant parts of our core business offerings, designed to address and manage ESG issues for clients, and to enable our clients to create more sustainable value. We view ESG risks as presenting an important opportunity for Aon to work together as one firm to address client needs and improve our impact on ESG matters.

REVIEW OF CONSOLIDATED RESULTS

Summary of Results

Our consolidated results are as follow (in millions, except per share data):

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We are exposed to potential fluctuations in earnings, cash flows, and the fair values of certain of our assets and liabilities due to changes in interest rates and foreign exchange rates. To manage the risk from these exposures, we enter into a variety of derivative instruments. We do not enter into derivatives or financial instruments for trading or speculative purposes.

The following discussion describes our specific exposures and the strategies we use to manage these risks. Refer to Note 2 “Summary of Significant Accounting Principles and Practices” of the Notes to Consolidated Financial Statements in Part II, Item 8 of this report for a discussion of our accounting policies for financial instruments and derivatives.

Foreign Exchange Risk

We are subject to foreign exchange rate risk. Our primary exposures include exchange rates between the U.S. dollar and the euro, the British pound, the Canadian dollar, the Australian dollar, the Indian rupee, and the Japanese yen. We use over-the-counter options and forward contracts to reduce the impact of foreign currency risk to our financial statements.

Additionally, some of our non-U.S. brokerage subsidiaries receive revenue in currencies that differ from their functional currencies. Our U.K. subsidiaries earn a portion of their revenue in U.S. dollars, euro, and Japanese yen, but most of their expenses are incurred in British pounds. At December 31, 2022, we have hedged approximately 45% of our U.K. subsidiaries’ expected exposures to the U.S. dollar, euro, and Japanese yen transactions for the years ending December 31, 2023 and 2024. We generally do not hedge exposures beyond three years.

We also use forward and option contracts to economically hedge foreign exchange risk associated with monetary balance sheet exposures, such as intercompany notes and current assets and liabilities that are denominated in a non-functional currency and are subject to remeasurement.

The potential loss in future earnings from foreign exchange derivative instruments resulting from a hypothetical 10% adverse change in year-end exchange rates would be $19 million and $9 million at December 31, 2023 and 2024, respectively.

The translated value of revenues and expenses from our international brokerage operations are subject to fluctuations in foreign exchange rates. If we were to translate prior year results at current year exchange rates, diluted earnings per share would have an unfavorable $0.33 impact during the year ended December 31, 2022. Further, adjusted diluted earnings per share, a non-GAAP measure as defined and reconciled under the caption “Review of Consolidated Results — Adjusted Diluted Earnings Per Share,” would have an unfavorable $0.44 impact during the year ended December 31, 2022 if we were to translate prior year results at current quarter exchange rates.

Interest Rate Risk

Our fiduciary investment income is affected by changes in international and domestic short-term interest rates. We monitor our net exposure to short-term interest rates and, as appropriate, hedge our exposure with various derivative financial instruments. This activity primarily relates to brokerage funds held on behalf of clients in the U.S. and in continental Europe. A hypothetical, instantaneous parallel decrease in the year-end yield curve of 100 BPS would cause a decrease, net of derivative positions, of $67 million to each of 2023 and 2024 pretax income. A corresponding increase in the year-end yield curve of 100 BPS would cause an increase, net of derivative positions, of $67 million to each of 2023 and 2024 pre-tax income.

We have long-term debt outstanding, excluding the current portion, with a fair market value of $8.7 billion and $9.2 billion as of December 31, 2022 and December 31, 2021, respectively. The fair value was less than the carrying value by $1.1 billion at December 31, 2022, and $0.9 billion greater than the carrying value at December 31, 2021. A hypothetical 1% increase or decrease in interest rates would change the fair value by a decrease of 7% or an increase of 8%, respectively, at December 31, 2022.

We have selected hypothetical changes in foreign currency exchange rates, interest rates, and equity market prices to illustrate the possible impact of these changes; we are not predicting market events.

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, 2022 and 2021, 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, 2022, 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, 2022 and 2021, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2022, 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, 2022, 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 17, 2023, 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.

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

Chicago, Illinois

February 17, 2023

Aon plc

Consolidated Statements of Income

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None.

Evaluation of Disclosure Controls and Procedures

We have conducted an evaluation of the effectiveness of the design and operation of our disclosure controls and procedures, as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) as of the end of the period covered by this annual report of December 31, 2022. Based on this evaluation, our chief executive officer and chief financial officer concluded as of December 31, 2022 that our disclosure controls and procedures were effective such that the information relating to Aon, including our consolidated subsidiaries, required to be disclosed in our SEC reports is recorded, processed, summarized and reported within the time periods specified in SEC rules and forms, and is accumulated and communicated to Aon’s management, including our chief executive officer and chief financial officer, as appropriate to allow timely decisions regarding required disclosure.

Management’s Report on Internal Control Over Financial Reporting

Management of Aon plc is responsible for establishing and maintaining adequate internal control over financial reporting as defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act. The Company’s internal control over financial reporting is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with U.S. GAAP. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Under the supervision and with the participation of our senior management, including our Chief Executive Officer and Chief Financial Officer, we assessed the effectiveness of our internal control over financial reporting as of December 31, 2022. In making this assessment, we used the criteria set forth by the Committee of Sponsoring Organizations of the Treadway Commission in the Internal Control — Integrated Framework (2013 Framework). Based on this assessment, management has concluded our internal control over financial reporting is effective as of December 31, 2022.

The effectiveness of our internal control over financial reporting as of December 31, 2022 has been audited by Ernst & Young, LLP, the Company’s independent registered public accounting firm, as stated in their report titled “Report of Independent Registered Public Accounting Firm on Internal Control over Financial Reporting.”

Changes in Internal Control Over Financial Reporting

No changes in Aon’s internal control over financial reporting (as defined in Rule 13a-15(f) under the Exchange Act) occurred during 2022 that have materially affected, or that are reasonably likely to materially affect, Aon’s internal control over financial reporting.

Report of Independent Registered Public Accounting Firm

To the Shareholders and the Board of Directors of Aon plc

Opinion on Internal Control over Financial Reporting

We have audited Aon plc’s internal control over financial reporting as of December 31, 2022, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 Framework), (the COSO criteria). In our opinion, Aon plc (the Company) maintained, in all material respects, effective internal control over financial reporting as of December 31, 2022, based on the COSO criteria.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated statements of financial position of the Company as of December 31, 2022 and 2021, 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, 2022, and the related notes and our report dated February 17, 2023 expressed an unqualified opinion thereon.

Basis for Opinion

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting included in the accompanying Management’s Report on Internal Control Over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. 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 audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects.

Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control Over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Chicago, Illinois

February 17, 2023

Not applicable.

Not applicable.

PART III

Information relating to Aon’s directors is set forth under the heading “Proposal 1 — Resolutions Regarding the Election of Directors” in the Proxy Statement for the 2023 Annual General Meeting of Shareholders (the “Proxy Statement”) and is incorporated herein by reference. Information relating to Aon’s executive officers is set forth in Part I of this report and is incorporated herein by reference. The remaining information required by this item is set forth under the headings “Director Nominee Bios” and “Corporate Governance” in the Proxy Statement, and all such information is incorporated herein by reference.

We have adopted a code of ethics that applies to the Company’s directors, officers, and employees, including the Chief Executive Officer, Chief Financial Officer, Controller, and Chief Accounting Officer and other persons performing similar functions. The text of our code of ethics, which we call our Code of Business Conduct, is available on our website as disclosed in Part 1 of this report. We will provide a copy of the code of ethics without charge upon request to the Company Secretary, Metropolitan Building, James Joyce Street, Dublin 1, Ireland. We will disclose on our website any amendment to or waiver from our code of ethics on behalf of any of our executive officers or directors.

Information relating to director and executive officer compensation is set forth under the headings “Compensation Committee Report,” “Compensation Discussion and Analysis,” and “Executive Compensation” in the Proxy Statement, and all such information is incorporated herein by reference.

The material incorporated herein by reference to the information set forth under the heading “Compensation Committee Report” in the Proxy Statement shall be deemed furnished, and not filed, in this Form 10-K and shall not be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended, or the Exchange Act as a result of this furnishing, except to the extent that it is specifically incorporated by reference by Aon.

Information relating to compensation committee interlocks and insider participation is set forth under the heading “Compensation Discussion and Analysis - Compensation Committee Interlocks and Insider Participation” in the Proxy Statement and is incorporated herein by reference.

Information relating to equity compensation plans and the security ownership of certain beneficial owners and management of Aon plc’s ordinary shares is set forth under the headings “Other Information - Equity Compensation Plan Information,” “Principal Holders of Voting Securities,” and “Security Ownership of Directors and Executive Officers” in the Proxy Statement, and all such information is incorporated herein by reference.

Information required by this Item is included under the headings “Corporate Governance — Director Independence” and “Certain Relationships and Related Transactions” in the Proxy Statement and is incorporated herein by reference.

Information required by this Item is included under the heading “Auditor Fees” in the Proxy Statement and is incorporated herein by reference.

PART IV

The following document has been included in Part II, Item 9.

All schedules for the Registrant and consolidated subsidiaries have been omitted because the required information is not present in amounts sufficient to require submission of the schedules or because the information required is included in the respective financial statements or notes thereto.

• Document has been previously filed with the SEC and is incorporated herein by reference herein. Unless otherwise indicated, such document was filed under Commission File Number 001-07933.

Indicates a management contract or compensatory plan or arrangement.

The registrant agrees to furnish to the SEC upon request a copy of (1) any long-term debt instruments that have been omitted pursuant to Item 601(b)(4)(iii)(A) of Regulation S-K, and (2) any schedules omitted with respect to any material plan of acquisition, reorganization, arrangement, liquidation or succession set forth above.

Item16. Form 10-K Summary

None.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.