Alliant Energy (LNT) 10-K risk factor changes: FY2025 vs FY2024

IPL and WPL may not receive an adequate amount of rate relief to recover all costs and earn their authorized rates of return, rates may be reduced, rate refunds may be required, rate adjustments may not be approved on a timely basis, costs may not be otherwise recovered through rates, earnings above certain thresholds may be required to be [removed: refunded,] [added: refunded or be used to reduce existing rate base of assets with higher levels of authorized return on equity,] recovery of capital expenditures, including those for electric distribution systems, above certain thresholds may be capped or not be allowed, rates may be temporarily frozen, such as IPL’s current retail electric rate base moratorium through September 2029, laws, rules or settlements may limit the ability to file rate adjustments or the period covered by a rate adjustment, regulatory decisions may limit the ability to defer recovery of and a return on prudently incurred costs in between rate reviews, certain rate base items may not receive a full weighted average cost of capital, and authorized rates of return on capital may be reduced.

[added: The impacts on our operations include: our ability to site] and [added: construct new energy facilities, such as renewable energy, energy storage projects, or natural gas-fired electric generating units (EGUs), and] recover [added: associated costs; our ability to decommission generating facilities and recover] related costs and the remaining carrying value of these facilities and related assets; MISO’s resource adequacy process establishing seasonal capacity planning reserve margin and capacity accreditation requirements, as well as additional changes to capacity accreditation, such as the direct loss of load methodology, impact how and when existing and new generating facilities such as IPL’s and WPL’s additional solar generation are accredited with energy capacity, and may require IPL and WPL to adjust their current resource plans, to add resources to meet the requirements of MISO’s seasonal resource adequacy process, or procure capacity whereby such costs might not be recovered in rates; [added: legislation or regulation that imposes mandatory integrated resource planning requirements, or materially changes existing resource planning standards, could delay approvals, require revisions to resource plans, increase compliance costs, and impact our ability to timely meet demand for energy from commercial and industrial customers, including data centers;] the impact of the lack of availability of existing and new generating facilities [removed: has] on our accredited capacity for such facilities pursuant to MISO’s seasonal resource adequacy process; IPL’s ability to achieve certain aggregate summer capacity factors under the consumer protection plan for its up to 400 MW of solar generation projects; the rates paid to transmission operators and how those costs are recovered from customers, including our ability to continue to use a transmission rider in Iowa; our ability to site, construct and recover costs for new natural gas pipelines; our ability to recover costs to upgrade our electric and gas distribution systems; the amount of certain sources of energy we must use, such as renewable sources; our ability to purchase generating facilities and recover the costs associated therewith; our ability to sell utility assets and any conditions placed upon the sale of such assets; our ability to enter into purchased power agreements and recover the costs associated therewith; the allocation of expenditures by transmission companies on transmission network upgrades and our ability to recover costs associated therewith; reliability; safety; the issuance of securities and ability to use other financing arrangements for our renewable energy projects; accounting matters; and transactions between affiliates.

These laws and regulations have imposed, and proposed laws and regulations could impose in the future, additional costs on our utility operations and requirements that impact our ability to continue operating [removed: electric generating units.][added: EGUs.]

This could affect the timing of retirement for our existing coal-fired [removed: electric generating units,] [added: EGUs,] and our need to add new fossil-fueled generation resources due to growing electric loads.

The extent of the U.S. Environmental Protection Agency’s proposed rules to regulate GHG emissions at fossil-fuel fired [removed: electric generating units] [added: EGUs] and specific impacts, including state plans to implement the emissions reductions, remains uncertain.

Regulation or legislation mandating GHG emissions reductions or other clean energy standards affecting utility companies could materially increase costs, causing some [removed: electric generating units] [added: EGUs] to be uneconomical to operate or maintain.

We are vulnerable to potential risks associated with the construction of [removed: electric generating units] [added: EGUs] that may extend to our supply chain and natural gas operations.

If the federal or state tax rates are increased, [added: state income tax apportionment is increased,] or we become subject to a corporate alternative minimum tax, we may experience adverse impacts to our financial condition and results of operations until those rates are reflected in our regulatory filings.

If energy storage facilities are not completed in the anticipated timeframe or investment tax credits are not able to be generated or sold due to the repeal or amendment of the Inflation Reduction Act of 2022, [added: or new limitations imposed by the OBBB Act,] we may experience adverse impacts on our financial condition and results of operations.

[removed: owned] [added: Energy demand may decrease due to many things, including economic conditions, proliferation of customer and third party-owned] generation, technological advances that reduce the costs of renewable energy and energy storage solutions for our customers, government policies, such as the Inflation Reduction Act of 2022, which incentivize customer and third party-owned generation, loss of service territory or franchises, energy efficiency measures, changes in customer usage due to rate design changes, such as time of use rates, technological advances that improve energy efficiency, third-party disrupters, loss of wholesale customers, loss of customers that pursue their own renewable projects to achieve specific sustainability goals, and the adverse impact of tariffs on our customers.

[removed: Demand for energy from high usage customers may impact our business -] The ability to serve significant new commercial or industrial customers on contract rates, including data centers, may require certain regulatory approvals, and the activities and costs related to the construction, acquisition or contracts for additional generation capacity and transmission required to meet the high demands of such customers could be significant.

The inability or delays in obtaining regulatory approvals [added: with acceptable conditions] or [removed: securing additional capacity] [added: providing sufficient generation] or [added: securing] transmission, due to supply chain risk, operational risk, or other factors, may impact our ability, or the cost, to provide energy to new [removed: customers, the contract rates may not fully recover the costs, the contracts may increase counterparty credit risk, and the costs to provide service may be higher than expected.][added: customers.]

The [removed: contract] [added: individual customer] rates for [removed: high usage] [added: large load growth] customers are subject to regulatory approvals and our regulatory authorities may change the rates we can charge and the costs that can be recovered.

A [removed: high usage] [added: large load growth] customer may decide not to take energy, take less energy than anticipated, or not take service on the anticipated schedule, due to changes in business needs, construction delays, technological advances that improve energy efficiency, or other factors, which may result in lower demand for energy than anticipated.

The addition of [removed: high usage] [added: large load growth] customers may increase the concentration of sales, and increase revenue and earnings volatility.

[added: These risks include: the inability to obtain necessary regulatory approvals and permits in a timely] manner; adverse interpretation or enforcement of permit conditions; changes in applicable laws or regulations; changes in costs of materials, equipment, commodities, fuel or labor including due to inflation, tariffs or labor issues; delays caused by construction accidents or injuries; shortages in materials, equipment, or qualified labor; changes to the scope or timing of the projects; general contractors, subcontractors, or equipment not performing as required under their contracts; the inability to agree to contract terms or disputes in contract terms; the inability to successfully resolve warranty claims; poor initial cost estimates; work stoppages; adverse weather conditions; government actions; legal action; unforeseen engineering or technology issues; limited access to capital or other financing arrangements; and other adverse economic conditions.

Storms and natural disasters may impact our customers and the resulting reduced demand for energy could cause [added: lower sales and revenues, which may not be replaced or recovered in rates, or rate recovery may be delayed.]

If we were unable to obtain enough natural gas or coal for our [removed: electric generating units] [added: EGUs] under our existing contracts, or to obtain electricity under existing or future purchased power agreements, we could be required to purchase natural gas or coal at higher prices, need to secure higher cost delivery of natural gas or coal, be forced to curtail the operation of our natural gas-fired or coal-fired generating facilities, be forced to purchase electricity from higher-cost generating resources in the MISO energy market and/or be required to purchase replacement capacity to comply with electric demand planning reserve margins.

Natural gas market prices have been volatile in the past and could be volatile in the future due to additional future regulations, increased demand including due to [added: new natural gas-fired generating facilities,] increased liquified natural gas demand from foreign countries, limited global suppliers of natural gas, periods of extremely cold temperatures or disruption in supply caused by major storms or pipeline explosions.

[added: Any work stoppage experienced in connection with negotiations of] collective bargaining agreements could adversely affect our financial condition and results of operations as well as our ability to implement our strategy.

We have forecasted capital expenditures of approximately [removed: $11] [added: $13] billion over the next four years.

IPL and WPL have entered into conditional commitments with the U.S. Department of [removed: Energy’s] [added: Energy Office of Energy Dominance Financing, formerly the] Loan Programs [removed: Office] [added: Office,] for loan guarantees of approximately $3 billion in aggregate and WPL has been selected for additional grants.

Risks Related to Data Center and Other Large Load Growth Customers

Demand from data centers and other large load growth customers may impact our business - Our ability to manage the development and implementation of complex business opportunities related to the growing demand for data centers may be limited by financial, operational, or regulatory factors.

We may enter into agreements requiring significant capital investment in generation and transmission capacity for large load growth customers before realizing any potential returns.

We may not be able to affordably and timely construct generation, or cause transmission companies to affordably and timely construct transmission infrastructure to meet potential load growth from any large load growth customer.

We may not be able to adequately protect against the risks inherent in relying on rapid growth within a small number of large customers in a single industry.

The individual customer rates may not provide sufficient revenues to fully recover the costs, the contracts with large load growth customers may increase counterparty credit risk, and the costs to provide service may be higher than expected.

Large load growth customers may not be able to meet obligations in our contracts, including the obligation to pay any termination charges.

Additionally, if pipeline expansions needed for new gas‑fired generation are delayed or not approved, we may be unable to meet peak requirements for data center load, increasing market purchases or capacity procurement costs.

Any of these circumstances could adversely affect our business, financial condition, results of operations and growth prospects.

Laws, regulations, and opposition to data centers may impact our business - Federal, state or local legislation, rulemaking, or siting standards that specifically restrict or delay the zoning, siting or operation of data centers could reduce or defer expected load growth and impair cost recovery for associated infrastructure.

Community opposition to data centers—driven by concerns about land use, water consumption, generation emissions, noise, or traffic—could result in permitting delays, litigation, project cancellations, or additional mitigation costs, reducing expected load growth.

As a result, we may experience adverse impacts on our financial condition and results of operations.

Legislative or regulatory changes that enable large load growth customers, including data centers, to own or procure on-site generation or to self-supply through sources behind-the-meter or behind-the-meter arrangements could materially reduce retail sales, shift cost recovery to remaining customers, and impact our ability to earn authorized rates of return.

We may not be able to meet our resource adequacy requirements if GHG regulations require us to shut down fossil fuel generating facilities before we can build new generating facilities to meet growing demand for electricity.

However, the One Big Beautiful Bill Act (OBBB Act) includes significant changes to renewable tax credits, including accelerating the termination of production tax credits and investment tax credits.

These changes may materially limit our ability to sell or transfer renewable tax credits at reasonable terms in future periods.

The OBBB Act’s early termination of production tax credits for projects beginning construction more than 12 months after enactment may also limit our ability to qualify new facilities for future production tax credits.

The Inflation Reduction Act and related guidance also include limitations on the use of components and/or financing from entities with ties to certain foreign countries.

If our generation or energy storage projects include equipment or subcomponents sourced from entities with ties to certain foreign countries, related production or investment tax credits may be reduced or denied, which could increase customer costs and adversely affect our financial condition.

The OBBB Act further expands limitations on the use of components and/or financing from entities with ties to certain foreign countries, which could reduce or disqualify renewable tax credits for generation and energy storage projects.

We may not realize anticipated or expected growth from large load growth customers, due to many factors, including changes in customers’ goals, changes in environmental policies, improvements in energy efficiency or technology, or competition from other companies.

We may not be able to provide sufficient transmission capacity in a timely manner or transmission providers may be unable to timely provide transmission upgrades to enable connecting new generation to the grid, which could delay expected system load demand from large load growth customers such as data centers, expose us to market purchases and reduce expected revenues.

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The impacts on our operations include: our ability to site and construct new energy facilities, such as renewable energy, energy storage projects, or natural gas-fired electric generating units, and recover associated costs; our ability to decommission generating facilities

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

Our regulators or legislatures could change regulations or laws to permit third parties to provide renewable energy directly to our customers without being treated as a utility, potentially causing a competitive disadvantage for us.

Energy demand may decrease due to many things, including economic conditions, proliferation of customer and third party-

These factors could negatively impact our financial condition and results of operations.

These risks include: the inability to obtain necessary regulatory approvals and permits in a timely

For example, WPL has notified the PSCW that its solar generating facility developments have exceeded the approved costs.

lower sales and revenues, which may not be replaced or recovered in rates, or rate recovery may be delayed.

Any work stoppage experienced in connection with negotiations of

This MDA includes information relating to Alliant Energy, IPL and [removed: WPL,] [added: WPL (collectively, the Utilities),] as well as [added: ATC Holdings,] AEF and Corporate Services.

In addition, this MDA includes certain financial information for [removed: 2024] [added: 2025] compared to [removed: 2023.][added: 2024.]

Refer to MDA in the combined [removed: 2023] [added: 2024] [Form [removed: 10-K](https://www.sec.gov/Archives/edgar/data/352541/000035254124000014/lnt-20231231.htm)] [added: 10-K](https://www.sec.gov/Archives/edgar/data/352541/000035254125000014/lnt-20241231.htm)] for details on certain financial information for [removed: 2023] [added: 2024] compared to [removed: 2022.][added: 2023.]

Alliant Energy’s mission is to deliver [removed: affordable] [added: the] energy solutions and exceptional service that its customers and [removed: the] communities [removed: it serves] count on - affordably, safely, [removed: reliably,] [added: reliably] and [removed: sustainably.][added: responsibly.]

This mission aligns with Alliant Energy’s purpose - to serve customers and build stronger communities - which guides it through the [removed: ever-changing] [added: evolving] dynamics of the economy and the energy industry.

Alliant Energy [removed: takes its responsibility] [added: leads] as a corporate [removed: citizen seriously and remains a careful steward of the environment] [added: citizen, advancing environmental stewardship] and [removed: supports] [added: supporting] the communities in its service territories.

Alliant Energy’s mission and purpose are supported by a strategy focused on meeting evolving customer expectations, [removed: providing an] [added: delivering] attractive [removed: return] [added: returns] for investors, and advancing emerging technologies [removed: with] [added: and generation to enable] safe, secure [added: and future-ready] energy production.

Providing affordable energy solutions for customers - Alliant Energy’s strategy focuses on affordable energy solutions that support retention and growth of [removed: its] existing customers and attract new customers to its service territories.

[removed: From 2022 through 2024,] Alliant [removed: Energy completed projects that resulted in approximately 1,500 MW of additional zero-fuel cost solar generation resources in aggregate (WPL completed 1,089 MW of solar generation in Wisconsin in 2022-2024] [added: Energy’s industry-leading wind] and [removed: IPL completed 400 MW of] solar [added: energy resources provide zero-fuel cost] generation [removed: in Iowa in 2024), which] [added: as well as] generate renewable tax credits that are provided to its electric customers.

- Alliant Energy, IPL and WPL have utilized, and expect to continue to utilize, various provisions of the Inflation Reduction Act of 2022 to enhance tax benefits [added: provided to customers that are] expected from wind, solar and energy storage projects in Iowa and Wisconsin, including transferring certain future tax credits from such projects to other corporate taxpayers.

Refer to [Note 1(c)](#i1fc9d0e18c654199a6dadea9bc41997a_211) for discussion of [added: $285 million,] $216 million and $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in [added: 2025,] 2024 and 2023, respectively.

- IPL and WPL have entered into conditional commitments with the U.S. Department of [removed: Energy’s] [added: Energy Office of Energy Dominance Financing, formerly the] Loan Programs [removed: Office] [added: Office,] for loan guarantees of approximately $1.4 billion and $1.6 billion, respectively.

If finalized, such loans would provide low interest financing for IPL’s and WPL’s expected construction of [removed: renewable generation and energy storage projects.][added: eligible projects as defined in the governing agreement.]

- In July 2024, the U.S. Department of Energy Office of [added: Electricity - formerly administered by the Office of] Clean Energy Demonstrations awarded WPL’s Columbia Energy Storage Project, an approximately 20 MW compressed CO2-based long-duration energy storage system at the Columbia Energy Center site, up to approximately $30 million in grant funding during construction of the project.

[removed: If finalized, any] [added: Any] grant proceeds [removed: would] [added: are expected to] reduce the cost of the [removed: projects] [added: project] for WPL’s customers.

Making customer-focused investments - Alliant Energy’s strategic priorities include making [removed: significant] customer-focused investments [removed: toward more] [added: to provide] reliable, resilient, and sustainable [removed: customer] energy solutions.

- Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately [removed: 1,200] [added: 1,600] MW of new [removed: wind and solar generation in aggregate,] [added: natural gas resources,] approximately 1,000 MW of [added: new] energy storage, approximately [removed: 750] [added: 1,300] MW of new [removed: natural gas resources, refurbishments at approximately 600 MW of existing wind farms, and] [added: renewable generation,] improvements [removed: at] [added: of] approximately [removed: 650] [added: 410] MW [removed: of] [added: at] existing natural gas-fired [removed: EGUs] [added: EGUs,] and [removed: the conversion] [added: refurbishments at approximately 450 MW] of existing [removed: coal-fired EGUs to natural gas.][added: wind farms.]

Alliant Energy is currently evaluating the impact of potential additional [added: demand from] large load growth customers and MISO’s seasonal resource adequacy requirements on its resource plans and will update these generation investment plans as needed in the future.

[removed: - Improving] [added: Electric system investments will focus on areas such as improving] reliability and resiliency with more underground electric [removed: distribution,] [added: distribution] and [added: upgrades including automation and] enabling distributed energy [removed: solutions with higher capacity lines.][added: resources.]

[removed: - Installing] [added: Fiber Optic Telecommunication Network - Alliant Energy installed] fiber optic routes between [removed: Alliant Energy’s] [added: its] facilities to enhance its communications network to improve resiliency and reliability of, and enable and strengthen, the integrated grid network focused on less densely populated rural areas.

Growing customer demand - Alliant Energy’s strategy supports expanding electric and gas usage in its service territories by promoting electrification initiatives and economic [removed: development.][added: development to grow at the pace of its customers.]

In addition, Iowa’s Major Economic Growth Attraction program and [added: Iowa’s and] Wisconsin’s sales and use tax exemption for qualified data centers, encourage economic development in Alliant Energy’s service territory.

The [added: energy resources to serve this expected load are included in the construction and acquisition table in “[Liquidity and Capital Resources](#i3fd6d02a42fa4a0d9f724c22f6fbf01c_82795).” The] actual timing and amount of increases in IPL’s [added: and WPL’s] load are subject to various factors, including interconnections and actual customer demand, and any executed or future agreements with customers are not expected to result in immediate increases in load.

- Various development-ready sites, which [added: have transmission capabilities,] are rail-served and in close proximity to a variety of transportation options, are located throughout Alliant Energy’s service territories.

| Utilities and Corporate Services | | | [removed: $722] [added: $875] | | | | | | [removed: $2.81] [added: $3.39] | | | | | | [removed: $724] [added: $722] | | | | | | [removed: $2.86] [added: $2.81] | | |

| ATC Holdings | | | [removed: 40] [added: 41] | | | | | | 0.16 | | | | | | [removed: 35] [added: 40] | | | | | | [removed: 0.14] [added: 0.16] | | |

| Non-utility and Parent | | | [removed: (72)] [added: (106)] | | | | | | [removed: (0.28)] [added: (0.41)] | | | | | | [removed: (56)] [added: (72)] | | | | | | [removed: (0.22)] [added: (0.28)] | | |

| Alliant Energy Consolidated | | | [removed: $690] [added: $810] | | | | | | [removed: $2.69] [added: $3.14] | | | | | | [removed: $703] [added: $690] | | | | | | [removed: $2.78] [added: $2.69] | | |

Alliant Energy’s Utilities and Corporate Services net income [removed: decreased] [added: increased] by [removed: $2] [added: $153] million in [removed: 2024] [added: 2025] compared to [removed: 2023.][added: 2024.]

The [removed: decrease] [added: increase] was primarily due to [added: higher revenue requirements from capital investments, estimated temperature impacts on retail electric and gas sales,] an asset valuation charge for IPL’s Lansing Generating Station as a result of the IUC order for IPL’s retail electric rate [removed: review, estimated temperature impacts on retail electric and gas sales,] [added: review in 2024,] restructuring and voluntary separation [removed: charges,] [added: charges in 2024, and] an ARO charge allocated to the steam business at IPL due to the revised CCR [removed: Rule, higher depreciation and financing expenses, and lower AFUDC.][added: Rule in 2024.]

Alliant Energy’s Non-utility and Parent net income decreased by [removed: $16] [added: $34] million in [removed: 2024] [added: 2025] compared to [removed: 2023,] [added: 2024,] primarily due to [added: an asset valuation charge for Alliant Energy’s non-utility business in 2025,] higher financing [removed: expense.][added: expense and a state income tax apportionment charge in 2025, partially offset by an adjustment of deferred tax assets due to Iowa tax reform in 2024.]

Net Income Variances - The following items contributed to increased (decreased) net income for [removed: 2024] [added: 2025] compared to [removed: 2023] [added: 2024] (in millions):

| Changes in electric utility (Refer to [details below](#i29dd73abc2114eb3bf707729382758d7_66303)) | | | [removed: $27] [added: $325] | | | | | | [removed: ($14)] [added: $149] | | | | | | [removed: $41] [added: $176] | | |

| Changes in gas utility (Refer to [details below](#i29dd73abc2114eb3bf707729382758d7_66304)) | | | [removed: (75)] [added: 60] | | | | | | [removed: (50)] [added: 15] | | | | | | [removed: (25)] [added: 45] | | |

| Changes in other utility | | | [removed: 2] [added: (3)] | | | | | | [removed: —] [added: (2)] | | | | | | [removed: 2] [added: (1)] | | |

| Changes in total revenues | | | [removed: (46)] [added: 381] | | | | | | [removed: (64)] [added: 162] | | | | | | [removed: 18] [added: 220] | | |

| Changes in electric production fuel and purchased power (Refer to [details below](#i29dd73abc2114eb3bf707729382758d7_66305)) | | | [removed: 108] [added: (114)] | | | | | | [removed: 13] [added: (14)] | | | | | | [removed: 96] [added: (100)] | | |

| Changes in electric transmission service (Refer to [details below](#i29dd73abc2114eb3bf707729382758d7_66306)) | | | [removed: (30)] [added: (12)] | | | | | | [removed: 3] [added: (5)] | | | | | | [removed: (33)] [added: (7)] | | |

| Changes in cost of gas sold (Refer to [details below](#i29dd73abc2114eb3bf707729382758d7_66307)) | | | [removed: 75] [added: (39)] | | | | | | [removed: 43] [added: (7)] | | | | | | [removed: 33] [added: (32)] | | |

| Asset valuation charge for IPL’s Lansing Generating Station in 2024 (Refer to [Note 2](#i1fc9d0e18c654199a6dadea9bc41997a_250) for details) | | | [removed: (60)] [added: 60] | | | | | | [removed: (60)] [added: 60] | | | | | | — | | |

- Alliant Energy’s resource plan is the roadmap for building a strong and resilient energy future to meet the growing energy needs across Iowa and Wisconsin.

This long-term plan expands generation capacity and includes a balanced mix of natural gas, energy storage, new renewable generation, improvements at existing natural gas-fired EGUs and refurbishments at existing wind farms.

It is designed to deliver the reliable, affordable energy customers count on by efficiently increasing the capabilities of existing generation through gas and wind facility upgrades while also building larger scale natural gas facilities to capture economies of scale.

By enhancing new and existing energy sources while maximizing traditional energy sources, Alliant Energy is helping support economic growth, maintain reliability and keep customer bills affordable.

At the same time, Alliant Energy is modernizing its distribution system to create a smarter, more adaptable infrastructure that increases resiliency and supports evolving energy technologies.

By advancing a responsible approach to energy resources, Alliant Energy can deliver what matters most to the customers and communities it serves - affordably, safely and reliably.

- Higher electric capacity revenues from existing generation resources beginning in 2025 are expected to provide cost benefits to WPL’s retail electric customers in the future through its fuel cost recovery mechanism.

- IPL provided billing credits to its retail electric customers through the tax benefit rider of $52 million and $16 million in 2025 and 2024, respectively.

IPL also provided its retail electric customers $162 million and $40 million in credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism in 2025 and 2024, respectively.

Refer to [Note 12](#i1fc9d0e18c654199a6dadea9bc41997a_301) for discussion of this program.

- In April 2025, WPL submitted an application to the U.S. Army Corps of Engineers for up to $45 million in loans through the Corps Water Infrastructure Financing Program.

If finalized, such loans would provide low interest financing for various proposed safety projects at WPL’s Kilbourn and Prairie du Sac hydro EGUs.

- IPL and WPL executed agreements to enable fiber connectivity to one of its data center customers by leasing underground conduit in their service territories, which is expected to provide cost benefits to IPL’s and WPL’s existing customers.

Alliant Energy’s capital allocation strategy is focused on:

- Growth: Developing energy resources to meet demand for future phases of economic development and transmission investments through ATC.

- Reliability and Resiliency: Investments to extend the flexibility, efficiency, capacity and optionality of existing resources including coal plant conversions and replacements, resiliency investments in natural gas storage, liquified natural gas and gas delivery, as well as reliability and safety investments in electric and gas distribution.

- Customer Value: Improving customer and employee experiences through technology investments that increase operational efficiency, service effectiveness and organizational agility.

- Completion of construction of energy storage projects totaling 175 MW at WPL and 99MW at IPL in 2025.

- Completion of the Neenah Unit 1 and Sheboygan Falls Unit 1 advanced gas path projects in 2025, which increased the efficiency and capacity at each of these facilities.

- IPL has entered into electric service agreements with two new customers, and WPL has entered into an electric service agreement with one new customer, each of whom is constructing or expects to construct one or more data centers in IPL’s or WPL’s service territories.

IPL’s and WPL’s currently executed electric service agreements include aggregate, peak demands of approximately 3 gigawatts.

- In May 2025 and October 2025, the IUC issued orders, with certain conditions, approving individual customer rates for data centers expected to be constructed in IPL’s service territory.

In April 2025, WPL filed a request with the PSCW for approval of an individual customer rate for a data center expected to be constructed in its service territory.

| | | | 2025 | | | | | | | | | | | | 2024 | | | | | | | | |

| Changes in non-utility | | | (1) | | | | | | — | | | | | | — | | |

| Changes in equity income from unconsolidated investments, net (Refer to [Note 6](#i1fc9d0e18c654199a6dadea9bc41997a_268) for details) | | | (1) | | | | | | — | | | | | | — | | |

| Changes in AFUDC | | | 14 | | | | | | 13 | | | | | | 1 | | |

| | | | 2025 | | | | | | 2024 | | | | | | | | | | | | 2025 | | | | | | 2024 | | | | | | | | | | | | 2025 | | | | | | 2024 | | | | | | 2025 | | | | | | 2024 | | |

| Retail | | | $3,305 | | | | | | $3,009 | | | | | | | | | | | | 25,122 | | | | | | 24,569 | | | | | | | | | | | | $472 | | | | | | $419 | | | | | | 49,363 | | | | | | 43,489 | | |

| | | | $3,697 | | | | | | $3,372 | | | | | | | | | | | | 33,129 | | | | | | 33,029 | | | | | | | | | | | | $525 | | | | | | $465 | | | | | | 172,504 | | | | | | 166,875 | | |

| Retail | | | $1,801 | | | | | | $1,662 | | | | | | | | | | | | 13,882 | | | | | | 13,620 | | | | | | | | | | | | $234 | | | | | | $223 | | | | | | 23,710 | | | | | | 21,640 | | |

| | | | $1,896 | | | | | | $1,747 | | | | | | | | | | | | 16,171 | | | | | | 15,540 | | | | | | | | | | | | $265 | | | | | | $250 | | | | | | 68,199 | | | | | | 64,715 | | |

| | | | $1,801 | | | | | | $1,625 | | | | | | | | | | | | 16,958 | | | | | | 17,489 | | | | | | | | | | | | $260 | | | | | | $215 | | | | | | 104,305 | | | | | | 102,160 | | |

| Lower revenues at IPL due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (offset by changes in income taxes) (a) | | | (122) | | | | | | (122) | | | | | | — | | |

| Lower revenues at IPL from discontinuation of renewable energy rider in 2024 (a) | | | (24) | | | | | | (24) | | | | | | — | | |

| Lower wholesale revenues at IPL primarily due to lower sales from the expiration of IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative in 2025 | | | (22) | | | | | | (22) | | | | | | — | | |

| | | | $325 | | | | | | $149 | | | | | | $176 | | |

| | | | $60 | | | | | | $15 | | | | | | $45 | | |

| Higher electric production fuel costs (a) | | | ($63) | | | | | | ($41) | | | | | | ($22) | | |

| | | | ($114) | | | | | | ($14) | | | | | | ($100) | | |

| | | | 27 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

- Alliant Energy’s resource plan continues to add resources in Iowa and Wisconsin, which is expected to result in continued reliability and affordability for its utility customers.

As a result, Alliant Energy directly reinvests in the communities it serves through the addition of skilled jobs, economic development and increased tax revenue.

The Inflation Reduction Act of 2022 is expected to result in more cost benefits for IPL’s and WPL’s customers, higher rate base amounts, and improvements in long-term cash flows over the life of the solar, energy storage and wind refurbishment projects.

- Significant fuel cost reductions beginning in 2023 with the completion of various solar facilities.

- Issuance of new long-term debt at historically low interest rates for IPL ($300 million of 3.1% senior debentures due 2051) and WPL ($300 million of 1.95% green bonds due 2031) in 2021 and WPL ($600 million of 3.95% green bonds due 2032) in 2022.

In addition, in October 2024, the U.S. Department of Energy Office of Grid Deployment selected WPL’s Smart Power Automation for Rural Communities program application to move into the final stage of award negotiations for up to $50 million in grant funding under the Grid Resilience and Innovation Partnerships Program.

Alliant Energy’s strategy drives a capital allocation process focused on: 1) transitioning its generation portfolio to meet the growing interest and needs of customers for reliable and sustainable sources of energy, 2) upgrading its electric and gas distribution systems to strengthen safety, reliability and resiliency, as well as enable distributed energy solutions in its service territories, and 3) enhancing its customers’ and employees’ experience with evolving technology and greater flexibility.

Currently, approximately 28% of Alliant Energy’s electric distribution system is underground.

Currently, approximately 1,000 miles of underground fiber optic routes have been installed.

- IPL has entered into electric service agreements with two new customers, who currently expect to build data centers at the Big Cedar Industrial Center in Cedar Rapids, Iowa in IPL’s service territory.

These agreements include aggregate, maximum demands of approximately 1.9 gigawatts.

The electric service agreements are subject to IUC approval under the individual customer rate tariff that was included in the IUC’s September 2024 order for IPL’s retail electric rate review.

| | | | 2024 | | | | | | | | | | | | 2023 | | | | | | | | |

These items were partially offset by higher revenue requirements from capital investments.

| | | | | | | | | | | | | | | | | | |

| Changes in AFUDC (Primarily due to changes in levels of CWIP balances related to solar generation and energy storage, and IPL’s refurbishment of the existing Franklin County wind farm) | | | (25) | | | | | | 22 | | | | | | (47) | | |

| | | | 2024 | | | | | | 2023 | | | | | | | | | | | | 2024 | | | | | | 2023 | | | | | | | | | | | | 2024 | | | | | | 2023 | | | | | | 2024 | | | | | | 2023 | | |

| Retail | | | $3,009 | | | | | | $3,008 | | | | | | | | | | | | 24,569 | | | | | | 24,940 | | | | | | | | | | | | $419 | | | | | | $495 | | | | | | 43,489 | | | | | | 46,405 | | |

| | | | $3,372 | | | | | | $3,345 | | | | | | | | | | | | 33,029 | | | | | | 32,587 | | | | | | | | | | | | $465 | | | | | | $540 | | | | | | 166,875 | | | | | | 161,582 | | |

| Retail | | | $1,662 | | | | | | $1,661 | | | | | | | | | | | | 13,620 | | | | | | 13,909 | | | | | | | | | | | | $223 | | | | | | $273 | | | | | | 21,640 | | | | | | 23,128 | | |

| | | | $1,747 | | | | | | $1,761 | | | | | | | | | | | | 15,540 | | | | | | 16,172 | | | | | | | | | | | | $250 | | | | | | $300 | | | | | | 64,715 | | | | | | 66,360 | | |

| | | | $1,625 | | | | | | $1,584 | | | | | | | | | | | | 17,489 | | | | | | 16,415 | | | | | | | | | | | | $215 | | | | | | $240 | | | | | | 102,160 | | | | | | 95,222 | | |

| Deferral of incremental solar generation construction costs at WPL in 2024 (Refer to [Note 3](#i1fc9d0e18c654199a6dadea9bc41997a_253)) | | | 12 | | | | | | — | | | | | | 12 | | |

| Lower wholesale revenues at WPL primarily due to lower fuel-related costs and lower sales | | | (13) | | | | | | (1) | | | | | | (12) | | |

| | | | $27 | | | | | | ($14) | | | | | | $41 | | |

Alliant Energy’s increase was partially offset by decreased sales for resale bulk power and other revenues at IPL primarily due to lower prices for electricity and capacity sold by IPL to MISO wholesale energy markets.

| | | | ($75) | | | | | | ($50) | | | | | | ($25) | | |

| Lower electric production fuel costs (a) | | | $108 | | | | | | $72 | | | | | | $36 | | |

| | | | $108 | | | | | | $13 | | | | | | $96 | | |

Electric production fuel costs decreased at WPL primarily due to lower natural gas prices in 2024 compared to 2023, and higher dispatch of WPL’s renewable EGUs in 2024, partially offset by higher coal volumes due to higher dispatch of WPL’s coal-fired EGU’s in 2024.

| | | | ($30) | | | | | | $3 | | | | | | ($33) | | |

| | | | $75 | | | | | | $43 | | | | | | $33 | | |

| | | | ($1) | | | | | | ($5) | | | | | | ($8) | | |

- Financing Plans - Alliant Energy currently expects to issue up to $25 million of common stock in 2025 through its Shareowner Direct Plan.

IPL and AEF each have $300 million of long-term debt maturing in 2025.

- Cash Flows From Operating Activities - Alliant Energy, IPL and WPL currently expect an increase in future cash flows from operating activities resulting from the transfer of future renewable tax credits to other corporate taxpayers pursuant to the Inflation Reduction Act of 2022.

In addition, Alliant Energy, IPL and WPL currently expect an increase in future cash flows from operating activities resulting from higher earnings on increasing rate base at IPL and WPL.

- Sales Trends and Temperatures - In July 2025, IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative (SMEC) will expire (sales to SMEC represented approximately 5% of IPL’s total electric sales in 2024), which is not expected to have a material impact on Alliant Energy’s or IPL’s future financial condition and results of operations.

Alliant Energy’s primary focus is to provide regulated electric and natural gas service to approximately [removed: 1,000,000] [added: 1,010,000] electric and approximately [removed: 430,000] [added: 435,000] natural gas customers in the Midwest through its two public utility subsidiaries, IPL and WPL.

At December 31, [removed: 2024,] [added: 2025,] IPL supplied electric and natural gas service to approximately [removed: 500,000] [added: 505,000] and 230,000 retail customers, respectively, in Iowa.

IPL [removed: is] also [added: sells electricity to wholesale customers in Illinois and Iowa and was] engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa, which [removed: are] [added: were] each under contract through 2025 for taking minimum quantities of annual steam usage, with certain [removed: conditions, after which IPL expects to exit the steam business.][added: conditions.]

At December 31, [removed: 2024,] [added: 2025,] WPL supplied electric and natural gas service to approximately [removed: 500,000] [added: 505,000] and [removed: 200,000] [added: 205,000] retail customers, respectively.

ATC Holdco LLC holds an interest in Duke-American Transmission Company, LLC, [added: which holds] a [removed: joint venture between Duke Energy Corporation and ATC, that owns] [added: note receivable related to the previously owned] electric transmission infrastructure in North America.

Travero - is a supply chain solutions company, including a short-line rail freight service in Iowa; a Mississippi River barge, rail and truck freight terminal in Illinois; freight brokerage services; [removed: wind turbine blade recycling services;] and a rail-served warehouse in Iowa.

Employees - At December 31, [removed: 2024,] [added: 2025,] Alliant Energy, IPL and WPL had the following full- and part-time employees:

| Alliant Energy | | | [removed: 2,998] [added: 2,948] | | | | | | [removed: 1,732] [added: 1,705] | | | | | | 58% | | |

Through a variety of [removed: health, welfare and compensation] programs, we offer employees choice and control, and help support their financial, physical, and mental well-being.

We [added: also] provide [removed: tools and resources] [added: a personal family advocate] to [added: help] employees [added: navigate their healthcare needs as well as other resources] to help maintain and improve their health.

[removed: Short-] [added: - competitive short-] and long-term incentive [removed: plans have a mix of operational and financial metrics] [added: compensation] that align employees with strategic corporate [removed: goals.][added: goals;]

- healthcare and insurance benefits, including medical, vision, dental, [added: mental health resources,] life, short-term disability, and long-term disability insurance;

- Learning: We offer various learning opportunities for employees, such as participating in area summits, supporting [added: and engaging with] company-wide [removed: listening sessions,] [added: Communities of Purpose,] providing training opportunities, and hosting [removed: speakers,] [added: speakers where employees can ask questions and interact with business leaders and other experts,] among other programs, as well as leaders facilitating conversations around employee engagement, helping to ensure employees are seen, heard and valued;

To help attract and introduce a wide range of candidates to our industry, we have early careers programs that include [removed: apprenticeships,] youth programs (high [removed: school)] [added: school), pre-apprenticeships,] and [removed: internships (college).][added: apprenticeships.]

[added: The] Midwest Reliability Organization, which is a regional member of North American Electric Reliability Corporation, has direct responsibility for mandatory electric reliability standards for IPL and WPL.

New Electric Generating Units - A CA application is required to be filed with the PSCW for construction approval of any new EGU [removed: (including] [added: or] energy [removed: storage)] [added: storage] with a capacity of less than 100 MW and a project cost of $16.3 million or more.

WPL must obtain a CPCN from the PSCW in order to construct a new EGU [removed: (including] [added: or] energy [removed: storage)] [added: storage] in Wisconsin with a capacity of 100 MW or more.

Department of Homeland Security Transportation Security Administration - Alliant Energy, IPL and WPL are subject to regulation for physical and cybersecurity of their natural gas pipeline [removed: systems, and are applying, and monitoring for changes to, these requirements to their pipeline] systems.

In 2009, the EPA issued a ruling that found GHG emissions [added: from motor vehicles] contribute to climate change and therefore threaten public health and welfare, which is the basis for implementing CO2 reduction standards under the CAA.

[removed: *Clean Air] [added: *Cl*ean *Air] Act Section 111(d)* [removed: -] [added: \-] In May 2024, the EPA enacted the final Section 111(d) rule under the CAA for certain fossil-fueled EGUs, which requires states to implement plans to reduce CO2 emissions through various Best System of Emission Reduction (BSER) measures at affected sources, including retirement, enforceable limits on operational capacity, co-firing with low-GHG fuels, or carbon capture and [removed: energy] storage technology.

The final rule’s compliance requirements will be phased in beginning in 2030 and covers fossil-fueled EGUs that utilize steam boilers to generate electricity, including IPL’s coal-fired Ottumwa Generating Station, George Neal Generating Station, [removed: Prairie Creek Generating Station Unit 3] and Louisa Generating Station, WPL’s coal-fired Edgewater Generating Station Unit 5 [removed: (WPL currently plans to convert Edgewater Unit 5 to natural gas in 2028, subject to regulatory approvals),] and [added: Columbia Units 1 and 2, and] IPL’s natural gas-fired Burlington Generating Station and Prairie Creek Generating Station [removed: Unit] [added: Units 3 and] 4.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing [added: or potential] litigation.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these revised standards, including resolution of ongoing [added: or potential] litigation.

[added: IPL and] WPL currently [removed: receives,] [added: receive,] and expects to receive in the future, enough CSAPR emission allowances to ensure ongoing compliance without the need to purchase additional allowances or materially curtail operations.

[removed: As a result,] Alliant [removed: Energy and] [added: Energy,] IPL [added: and WPL] are currently unable to predict with certainty the future outcome or [removed: impacts] [added: impact] of these [removed: matters.][added: matters, including resolution of ongoing or potential litigation.]

The new limitations will be implemented in each facility’s wastewater discharge permits issued by state [removed: agencies and become effective as soon as possible but no later than December 31, 2029.][added: agencies.]

3) STRATEGY - Refer to “[Overview](#i1fc9d0e18c654199a6dadea9bc41997a_97)” in MDA for discussion of Alliant Energy’s strategy, which supports its mission to deliver energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and [removed: sustainably.][added: responsibly.]

Alliant Energy’s utility business [added: (electric and gas)] includes the operations of IPL [removed: (electric, gas] and [removed: steam operations) and WPL (electric and gas operations),] [added: WPL,] which are both reportable segments.

[removed: ][added: ]

IPL also sells electricity to wholesale customers in [removed: Minnesota and] Illinois.

Customers \- IPL and WPL provide electric utility service to a large base of retail customers in several industries, with the largest concentrations in the farming, agriculture, industrial manufacturing, chemical (including ethanol), [added: pipeline transportation,] packaging and food [removed: industries.][added: industries, and data centers.]

Competition - Retail electric customers in Iowa and Wisconsin currently do not have the ability to choose their electric supplier, and IPL and WPL have obligations to serve all [removed: their] retail electric [removed: customers.][added: customers in their service territories.]

Although electric service in Iowa and Wisconsin is regulated, IPL and WPL [removed: still] face competition from self-generation by large industrial customers, customer- and third party-owned generation (e.g. solar panels), alternative energy sources, and petitions to municipalize (Iowa) as well as service territory expansions by municipal utilities through annexations (Wisconsin).

Alliant Energy’s strategy includes actions to retain current customers and attract new customers into IPL’s and WPL’s service territories in an effort to keep energy rates low for all [removed: of their] customers.

Electric Supply - Alliant Energy, IPL and WPL have met, and expect to continue meeting, customer demand [removed: of] [added: for] electricity through a mix of electric supply, including owned EGUs, PPAs and additional purchases from wholesale energy markets.

Alliant Energy expects its current mix of electric supply to continue to evolve with new [removed: wind and solar] [added: renewable] generation, energy storage facilities, new natural gas resources, refurbishing of existing wind farms, improvements at existing natural gas-fired EGUs and converting certain coal-fired EGUs to natural gas.

| | | | June [removed: 2025] [added: 2026] - August [removed: 2025] [added: 2026] | | | | | | September [removed: 2025] [added: 2026] - November [removed: 2025] [added: 2026] | | | | | | December [removed: 2025] [added: 2026] - February [removed: 2026] [added: 2027] | | | | | | March [removed: 2026] [added: 2027] - May [removed: 2026] [added: 2027] | | |

| Required unforced capacity reserve margin | | | 7.9% | | | | | | [removed: 14.9%] [added: 11.6%] | | | | | | [removed: 18.4%] [added: 18.9%] | | | | | | [removed: 25.3%] [added: 23.4%] | | |

| | | | [removed: 2024] [added: 2025] | | | | | | [removed: 2023] [added: 2024] | | | | | | [removed: 2022] [added: 2023] | | | | | | [removed: 2024] [added: 2025] | | | | | | [removed: 2023] [added: 2024] | | | | | | [removed: 2022] [added: 2023] | | |

| All fuels | | | [removed: $2.49] [added: $2.81] | | | | | | [removed: $2.83] [added: $2.49] | | | | | | [removed: $4.37] [added: $2.83] | | | | | | [removed: $2.74] [added: $3.11] | | | | | | [removed: $3.09] [added: $2.74] | | | | | | [removed: $4.47] [added: $3.09] | | |

Subsequent to December 31, 2025, IPL exited the steam business.

| IPL | | | 1,003 | | | | | | 739 | | | | | | 74% | | |

| WPL | | | 992 | | | | | | 853 | | | | | | 86% | | |

IPL would apply excess earnings to the remaining net book value of IPL’s highest earning asset with advance ratemaking principles based on its authorized return on common equity.

In February 2026, the EPA finalized a rule to rescind its 2009 finding that GHG contributes to climate change, concluding that regulation of GHG falls outside of the scope of the CAA.

In addition, the final rule does not impact existing natural gas-fired combustion turbines.

In June 2025, the EPA proposed to repeal CAA Section 111(d) and a final rule is expected in the first half of 2026.

The proposed repeal has delayed the submittal of state plans for EPA approval by the May 2026 deadline.

In June 2025, the EPA proposed to repeal the May 2024 111(b) revised standards and a final rule is expected in the first half of 2026.

In January 2026, EPA finalized updates to the NSPS for combustion turbines built, reconstructed, or modified after December 13, 2024.

The rule established revised nitrogen oxides emission limits based on the size, capacity factor, efficiency, and fuel type for new, reconstructed or modified combustion turbines.

The rule maintained the prior sulfur dioxide emission limits.

Alliant Energy, IPL and WPL expect to be able to comply with the updated NSPS requirements and will continue to monitor potential litigation.

In December 2025, EPA finalized an extended timeframe for the new requirements, which must now be implemented no later than December 31, 2034.

In February 2026, the EPA issued a final rule extending certain compliance deadlines under the CCR Rule.

IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative expired in 2025.

| Required installed capacity reserve margin | | | 15.0% | | | | | | 22.1% | | | | | | 42.2% | | | | | | 42.0% | | |

| | | | 2025 | | | | | | 2024 | | | | | | 2023 | | | | | | 2025 | | | | | | 2024 | | | | | | 2023 | | |

| | | | 2025 | | | | | | 2024 | | | | | | 2023 | | | | | | 2025 | | | | | | 2024 | | | | | | 2023 | | |

Subsequent to December 31, 2025, IPL exited the steam business.

| | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- |

| | | | 3 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

IPL also sells electricity to wholesale customers in Minnesota (IPL’s related wholesale power agreement expires July 2025), Illinois and Iowa.

| IPL | | | 1,043 | | | | | | 759 | | | | | | 73% | | |

| WPL | | | 1,003 | | | | | | 860 | | | | | | 86% | | |

- competitive short- and long-term incentive compensation;

Electric Generating Unit Environmental Controls Projects \- At its sole discretion, IPL may submit an updated emissions plan and budget to the IUC setting out a multi-year plan and budget for managing regulated emissions from its coal-fired EGUs in a cost-effective manner.

IPL must simultaneously submit this plan and budget to the Iowa Department of Natural Resources for a determination of whether the plan and budget meet state environmental requirements for regulated emissions.

The reasonable and prudent costs associated with implementing the approved plan are expected to be included in IPL’s future retail electric rates.

State plans are subject to EPA approval, and must be submitted by May 2026.

If WPL’s coal-fired Columbia Energy Center is retired by the end of 2029, the final rule would not be applicable; however, if WPL converts Columbia Unit 1 and/or Unit 2 to natural gas, then the final rule would be applicable for the EGUs that are converted.

In addition, the final rule does not impact existing natural gas-fired combustion turbines, including IPL’s Marshalltown Generating Station and Emery Generating Station, and WPL’s Riverside Energy Center and West Riverside Energy Center; however, these EGUs could be subject to future Section 111(d) rules to reduce CO2 emissions from existing combustion turbines.

In 2023, the EPA finalized revisions to the CSAPR state-specific ozone season nitrogen oxides emission caps and utility-specific emission allowances for certain states, including Wisconsin, beginning in 2023; however, these revisions were stayed by the Supreme Court in June 2024.

In November 2024, the EPA issued an interim final rule to stay the 2023 rule and re-establish the prior emission caps and allowance allocations, including Wisconsin, pending judicial review.

These revisions do not currently apply to Iowa; however, Iowa could be included in a future rule.

In December 2024, the EPA proposed updates to the NSPS for combustion turbines built, reconstructed, or modified after December 13, 2024, which would establish more stringent emission limits for nitrogen oxides emissions and retain the current sulfur dioxide emission limits.

This proposal would establish size-based subcategories for new, reconstructed or modified combustion turbines, and could require combustion controls or selective catalytic reduction control equipment.

Alliant Energy, IPL and WPL are currently evaluating the proposed rule and are unable to predict with certainty future compliance impacts; however, costs to comply with this rule could have a material impact on their financial condition and results of operations.

| Required installed capacity reserve margin | | | 15.7% | | | | | | 25.3% | | | | | | 38.6% | | | | | | 38.8% | | |

Coal - Coal is one of the fuel sources for owned EGUs.

Refer to [Note](#i1fc9d0e18c654199a6dadea9bc41997a_3361) [](#i1fc9d0e18c654199a6dadea9bc41997a_3361)[1](#i1fc9d0e18c654199a6dadea9bc41997a_3361)[6](#i1fc9d0e18c654199a6dadea9bc41997a_3361)[(g)](#i1fc9d0e18c654199a6dadea9bc41997a_3361) for discussion of a court case and resulting FERC order, which decreased the base return on equity authorized for MISO transmission owners, including ATC.

For the fiscal year ended December 31, [removed: 2024][added: 2025]

[removed: ][added: ]

The aggregate market value of the voting and non-voting common equity held by nonaffiliates as of June 30, [removed: 2024:][added: 2025:]

Alliant Energy Corporation - [removed: $13.0] [added: $15.5] billion

Number of shares outstanding of each class of common stock as of January 31, [removed: 2025:][added: 2026:]

Alliant Energy Corporation, Common Stock, $0.01 par value, [removed: 256,692,381] [added: 257,140,829] shares outstanding

Portions of the Proxy Statement relating to Alliant Energy Corporation’s [removed: 2025] [added: 2026] Annual Meeting of Shareowners are, or will be upon filing with the Securities and Exchange Commission, incorporated by reference into Part III hereof.

| [Website Access to Reports](#i1fc9d0e18c654199a6dadea9bc41997a_16) | | | | | | | | | | | | | | | | | | [removed: [3](#i1fc9d0e18c654199a6dadea9bc41997a_16)] [added: [4](#i1fc9d0e18c654199a6dadea9bc41997a_16)] | | |

| [Part I.](#i1fc9d0e18c654199a6dadea9bc41997a_19) | | | [Item 1. Business](#i1fc9d0e18c654199a6dadea9bc41997a_22) | | | | | | | | | | | | | | | [removed: [3](#i1fc9d0e18c654199a6dadea9bc41997a_22)] [added: [4](#i1fc9d0e18c654199a6dadea9bc41997a_22)] | | |

| | | | [Item 1B. Unresolved Staff Comments](#i1fc9d0e18c654199a6dadea9bc41997a_67) | | | | | | | | | | | | | | | [removed: [22](#i1fc9d0e18c654199a6dadea9bc41997a_67)] [added: [23](#i1fc9d0e18c654199a6dadea9bc41997a_67)] | | |

| | | | [Item 2. Properties](#i1fc9d0e18c654199a6dadea9bc41997a_70) | | | | | | | | | | | | | | | [removed: [24](#i1fc9d0e18c654199a6dadea9bc41997a_70)] [added: [25](#i1fc9d0e18c654199a6dadea9bc41997a_70)] | | |

| | | | [Item 3. Legal Proceedings](#i1fc9d0e18c654199a6dadea9bc41997a_73) | | | | | | | | | | | | | | | [removed: [26](#i1fc9d0e18c654199a6dadea9bc41997a_73)] [added: [27](#i1fc9d0e18c654199a6dadea9bc41997a_73)] | | |

| | | | [Item 4. Mine Safety Disclosures](#i1fc9d0e18c654199a6dadea9bc41997a_76) | | | | | | | | | | | | | | | [removed: [26](#i1fc9d0e18c654199a6dadea9bc41997a_76)] [added: [27](#i1fc9d0e18c654199a6dadea9bc41997a_76)] | | |

| | | | [Information About Executive Officers](#i1fc9d0e18c654199a6dadea9bc41997a_79) | | | | | | | | | | | | | | | [removed: [26](#i1fc9d0e18c654199a6dadea9bc41997a_79)] [added: [27](#i1fc9d0e18c654199a6dadea9bc41997a_79)] | | |

| [Part II.](#i1fc9d0e18c654199a6dadea9bc41997a_82) | | | [Item 5. Market for Registrants’ Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities](#i1fc9d0e18c654199a6dadea9bc41997a_85) | | | | | | | | | | | | | | | [removed: [27](#i1fc9d0e18c654199a6dadea9bc41997a_85)] [added: [28](#i1fc9d0e18c654199a6dadea9bc41997a_85)] | | |

| | | | [Item 6.](#i1fc9d0e18c654199a6dadea9bc41997a_88) [\[Reserv](#i1fc9d0e18c654199a6dadea9bc41997a_88)[ed](#i1fc9d0e18c654199a6dadea9bc41997a_88)[\]](#i1fc9d0e18c654199a6dadea9bc41997a_88) | | | | | | | | | | | | | | | [removed: [27](#i1fc9d0e18c654199a6dadea9bc41997a_88)] [added: [28](#i1fc9d0e18c654199a6dadea9bc41997a_88)] | | |

| | | | [Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations](#i1fc9d0e18c654199a6dadea9bc41997a_94) | | | | | | | | | | | | | | | [removed: [27](#i1fc9d0e18c654199a6dadea9bc41997a_94)] [added: [28](#i1fc9d0e18c654199a6dadea9bc41997a_94)] | | |

| | | | [Item 7A. Quantitative and Qualitative Disclosures About Market Risk](#i1fc9d0e18c654199a6dadea9bc41997a_127) | | | | | | | | | | | | | | | [removed: [46](#i1fc9d0e18c654199a6dadea9bc41997a_127)] [added: [48](#i1fc9d0e18c654199a6dadea9bc41997a_127)] | | |

| | | | [Item 8. Financial Statements and Supplementary Data](#i1fc9d0e18c654199a6dadea9bc41997a_130) | | | | | | | | | | | | | | | [removed: [46](#i1fc9d0e18c654199a6dadea9bc41997a_130)] [added: [48](#i1fc9d0e18c654199a6dadea9bc41997a_130)] | | |

| | | | | | | [Alliant Energy Corporation](#i1fc9d0e18c654199a6dadea9bc41997a_133) | | | | | | | | | | | | [removed: [47](#i1fc9d0e18c654199a6dadea9bc41997a_133)] [added: [49](#i1fc9d0e18c654199a6dadea9bc41997a_133)] | | |

| | | | | | | [Interstate Power and Light Company](#i1fc9d0e18c654199a6dadea9bc41997a_157) | | | | | | | | | | | | [removed: [53](#i1fc9d0e18c654199a6dadea9bc41997a_157)] [added: [55](#i1fc9d0e18c654199a6dadea9bc41997a_157)] | | |

| | | | | | | [Wisconsin Power and Light Company](#i1fc9d0e18c654199a6dadea9bc41997a_178) | | | | | | | | | | | | [removed: [59](#i1fc9d0e18c654199a6dadea9bc41997a_178)] [added: [61](#i1fc9d0e18c654199a6dadea9bc41997a_178)] | | |

| | | | | | | [Combined Notes to Consolidated Financial Statements](#i1fc9d0e18c654199a6dadea9bc41997a_199) | | | | | | | | | | | | [removed: [65](#i1fc9d0e18c654199a6dadea9bc41997a_199)] [added: [67](#i1fc9d0e18c654199a6dadea9bc41997a_199)] | | |

| | | | | | | | | | [1. Summary of Significant Accounting Policies](#i1fc9d0e18c654199a6dadea9bc41997a_202) | | | | | | | | | [removed: [65](#i1fc9d0e18c654199a6dadea9bc41997a_202)] [added: [67](#i1fc9d0e18c654199a6dadea9bc41997a_202)] | | |

| | | | | | | | | | [2. Regulatory Matters](#i1fc9d0e18c654199a6dadea9bc41997a_250) | | | | | | | | | [removed: [71](#i1fc9d0e18c654199a6dadea9bc41997a_250)] [added: [73](#i1fc9d0e18c654199a6dadea9bc41997a_250)] | | |

| | | | | | | | | | [3. Property, Plant and Equipment](#i1fc9d0e18c654199a6dadea9bc41997a_253) | | | | | | | | | [removed: [74](#i1fc9d0e18c654199a6dadea9bc41997a_253)] [added: [76](#i1fc9d0e18c654199a6dadea9bc41997a_253)] | | |

| | | | | | | | | | [4. Jointly-owned Electric Utility Plant](#i1fc9d0e18c654199a6dadea9bc41997a_256) | | | | | | | | | [removed: [75](#i1fc9d0e18c654199a6dadea9bc41997a_256)] [added: [77](#i1fc9d0e18c654199a6dadea9bc41997a_256)] | | |

| | | | | | | | | | [5. Receivables](#i1fc9d0e18c654199a6dadea9bc41997a_259) | | | | | | | | | [removed: [76](#i1fc9d0e18c654199a6dadea9bc41997a_259)] [added: [77](#i1fc9d0e18c654199a6dadea9bc41997a_259)] | | |

| | | | | | | | | | [6. Investments](#i1fc9d0e18c654199a6dadea9bc41997a_268) | | | | | | | | | [removed: [77](#i1fc9d0e18c654199a6dadea9bc41997a_268)] [added: [78](#i1fc9d0e18c654199a6dadea9bc41997a_268)] | | |

| | | | | | | | | | [7. Common Equity](#i1fc9d0e18c654199a6dadea9bc41997a_274) | | | | | | | | | [removed: [77](#i1fc9d0e18c654199a6dadea9bc41997a_274)] [added: [79](#i1fc9d0e18c654199a6dadea9bc41997a_274)] | | |

| | | | | | | | | | [8](#i1fc9d0e18c654199a6dadea9bc41997a_280)[. Debt](#i1fc9d0e18c654199a6dadea9bc41997a_280) | | | | | | | | | [removed: [78](#i1fc9d0e18c654199a6dadea9bc41997a_280)] [added: [80](#i1fc9d0e18c654199a6dadea9bc41997a_280)] | | |

| | | | | | | | | | [9](#i1fc9d0e18c654199a6dadea9bc41997a_292)[. Leases](#i1fc9d0e18c654199a6dadea9bc41997a_292) | | | | | | | | | [removed: [81](#i1fc9d0e18c654199a6dadea9bc41997a_292)] [added: [84](#i1fc9d0e18c654199a6dadea9bc41997a_292)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_295)[0](#i1fc9d0e18c654199a6dadea9bc41997a_295)[. Revenues](#i1fc9d0e18c654199a6dadea9bc41997a_295) | | | | | | | | | [removed: [82](#i1fc9d0e18c654199a6dadea9bc41997a_295)] [added: [85](#i1fc9d0e18c654199a6dadea9bc41997a_295)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_298)[1](#i1fc9d0e18c654199a6dadea9bc41997a_298)[. Income Taxes](#i1fc9d0e18c654199a6dadea9bc41997a_298) | | | | | | | | | [removed: [83](#i1fc9d0e18c654199a6dadea9bc41997a_298)] [added: [86](#i1fc9d0e18c654199a6dadea9bc41997a_298)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_301)[2](#i1fc9d0e18c654199a6dadea9bc41997a_301)[. Benefit Plans](#i1fc9d0e18c654199a6dadea9bc41997a_301) | | | | | | | | | [removed: [85](#i1fc9d0e18c654199a6dadea9bc41997a_301)] [added: [89](#i1fc9d0e18c654199a6dadea9bc41997a_301)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_313)[3](#i1fc9d0e18c654199a6dadea9bc41997a_313)[. Asset Retirement Obligations](#i1fc9d0e18c654199a6dadea9bc41997a_313) | | | | | | | | | [removed: [94](#i1fc9d0e18c654199a6dadea9bc41997a_313)] [added: [97](#i1fc9d0e18c654199a6dadea9bc41997a_313)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_316)[4](#i1fc9d0e18c654199a6dadea9bc41997a_316)[. Derivative Instruments](#i1fc9d0e18c654199a6dadea9bc41997a_316) | | | | | | | | | [removed: [94](#i1fc9d0e18c654199a6dadea9bc41997a_316)] [added: [97](#i1fc9d0e18c654199a6dadea9bc41997a_316)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_322)[5](#i1fc9d0e18c654199a6dadea9bc41997a_322)[. Fair Value Measurements](#i1fc9d0e18c654199a6dadea9bc41997a_322) | | | | | | | | | [removed: [95](#i1fc9d0e18c654199a6dadea9bc41997a_322)] [added: [99](#i1fc9d0e18c654199a6dadea9bc41997a_322)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_328)[6](#i1fc9d0e18c654199a6dadea9bc41997a_328)[. Commitments and Contingencies](#i1fc9d0e18c654199a6dadea9bc41997a_328) | | | | | | | | | [removed: [97](#i1fc9d0e18c654199a6dadea9bc41997a_328)] [added: [101](#i1fc9d0e18c654199a6dadea9bc41997a_328)] | | |

| | | | | | | | | | [1](#i1fc9d0e18c654199a6dadea9bc41997a_352)[7](#i1fc9d0e18c654199a6dadea9bc41997a_352)[. Segments of Business](#i1fc9d0e18c654199a6dadea9bc41997a_352) | | | | | | | | | [removed: [100](#i1fc9d0e18c654199a6dadea9bc41997a_352)] [added: [103](#i1fc9d0e18c654199a6dadea9bc41997a_352)] | | |

Interstate Power and Light Company and Wisconsin Power and Light Company meet the conditions set forth in General Instruction I(1)(a) and (b) of Form 10-K and are therefore filing this Form 10-K with the reduced disclosure format specified in General Instruction I(2) to such Form 10-K.

- the impact of large load growth customers altering, delaying or cancelling planned facilities, including any resulting impacts of overbuilt or under-utilized transmission capacity or generation assets;

- any legislative or regulatory changes that impose mandatory integrated resource planning requirements or materially modify existing planning processes, potentially affecting resource selection, cost recovery, and the ability to meet large load growth demand for energy;

- risks associated with third-party risk management practices, including vendor financial condition, operational performance, cybersecurity incidents, and compliance with contractual and regulatory requirements;

- risks associated with large-scale internal technology modernization initiatives, including enterprise asset management systems, operational technology/informational technology integration, cloud transformation, and digital modernization, and the potential for delays, cost overruns, or operational impacts;

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| | | | 3 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

| | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- |

| | | | 22 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

The cybersecurity program is assessed against industry standards, including [removed: certain Center for Internet Security critical security controls.][added: the National Institute of Standards and Technology Cybersecurity Framework.]

The CIO reports to the Executive Vice President and [removed: CFO.][added: Chief Strategy Officer.]

The Audit Committee provides oversight of policies on risk assessment, controls, and accounting risk exposure, reviews cybersecurity disclosures in filings with the Securities and Exchange Commission, and reviews internal audit reports related to cybersecurity processes.

The Operations Committee provides focused oversight of operational and capital‑related cybersecurity and technology matters.

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| | | | 24 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

Electric - At December 31, [removed: 2024,] [added: 2025,] IPL’s and WPL’s facilities by primary fuel type were as follows:

| Marshalltown Generating Station (Units 1-3); Marshalltown, IA | | | | | | | | | | | | 2017 | | | | | | | | | | | | | | | | | | [removed: 652] [added: 666] | | |

| Marshalltown Combustion Turbines (Units 1-3); Marshalltown, IA | | | | | | | | | | | | 1978 | | | | | | | | | | | | | | | | | | [removed: 105] [added: 155] | | |

| Burlington Generating Station (Unit 1); Burlington, IA | | | | | | | | | | | | 1968 | | | | | | | | | | | | | | | | | | [removed: 131] [added: 143] | | |

| Burlington Combustion Turbines (Units 1-4); Burlington, IA | | | | | | | | | | | | 1994-1996 | | | | | | | | | | | | | | | | | | [removed: 37] [added: 34] | | |

| Total Gas | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 1,582] [added: 1,655] | | |

| Customer-hosted and Community Solar; various locations in IA | | | | | | | | | | | | [removed: 2024] [added: 2024-2025] | | | | | | | | | | | | | | | | | | [removed: 11] [added: 18] | | |

| Total Solar | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 419] [added: 426] | | |

| Ottumwa Generating Station (Unit 1); Ottumwa, IA (b) | | | | | | | | | | | | 1981 | | | | | | | | | | | | | | | | | | [removed: 339] [added: 336] | | |

| George Neal Generating Station (Unit 4); Sioux City, IA (c) | | | | | | | | | | | | 1979 | | | | | | | | | | | | | | | | | | [removed: 167] [added: 165] | | |

| George Neal Generating Station (Unit 3); Sioux City, IA (d) | | | | | | | | | | | | 1975 | | | | | | | | | | | | | | | | | | [removed: 140] [added: 143] | | |

| Prairie Creek Generating Station (Units 1 and 3); Cedar Rapids, IA [added: (e)] | | | | | | | | | | | | 1958-1997 | | | | | | | | | | | | | | | | | | [removed: 30] [added: 37] | | |

| Louisa Generating Station (Unit 1); Louisa, IA [removed: (e)] [added: (f)] | | | | | | | | | | | | 1983 | | | | | | | | | | | | | | | | | | 30 | | |

| Total Coal | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 706] [added: 711] | | |

| Lime Creek Combustion Turbines (Units 1-2); Mason City, IA | | | | | | | | | | | | 1991 | | | | | | | | | | | | | | | | | | [removed: 70] [added: 72] | | |

| Total Oil | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 70] [added: 72] | | |

| Total Energy Storage | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 9] [added: 108] | | |

| Total capacity | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 4,088] [added: 4,274] | | |

| Riverside Energy Center (Units 1-3); Beloit, WI | | | | | | | | | | | | 2004 | | | | | | | | | | | | | | | | | | [removed: 536] [added: 530] | | |

| West Riverside Energy Center (Units 1-3); Beloit, WI [removed: (f)] [added: (g)] | | | | | | | | | | | | 2020 | | | | | | | | | | | | | | | | | | [removed: 387] [added: 390] | | |

| Neenah Energy Facility (Units 1-2); Neenah, WI | | | | | | | | | | | | 2000 | | | | | | | | | | | | | | | | | | [removed: 292] [added: 296] | | |

| South Fond du Lac Combustion Turbines (2 Units); Fond du Lac, WI [removed: (g)] [added: (h)] | | | | | | | | | | | | 1994 | | | | | | | | | | | | | | | | | | [removed: 163] [added: 164] | | |

| Total Gas | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 1,378] [added: 1,380] | | |

| Forward Wind Energy Center (37 Units); Dodge and Fond du Lac Cos., WI [removed: (h)] [added: (i)] | | | | | | | | | | | | 2008 | | | | | | | | | | | | | | | | | | 59 | | |

| Customer-hosted and Community Solar; various locations in WI | | | | | | | | | | | | [removed: 2021-2022] [added: 2021-2025] | | | | | | | | | | | | | | | | | | [removed: 4] [added: 11] | | |

| Total Solar | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 1,095] [added: 1,102] | | |

| Columbia Energy Center (Units 1-2); Portage, WI [removed: (i)] [added: (j)] | | | | | | | | | | | | 1975-1978 | | | | | | | | | | | | | | | | | | [removed: 598] [added: 596] | | |

| Edgewater Generating Station (Unit 5); Sheboygan, WI | | | | | | | | | | | | 1985 | | | | | | | | | | | | | | | | | | [removed: 406] [added: 405] | | |

| Total Coal | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 1,004] [added: 1,001] | | |

| Total capacity | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [removed: 3,985] [added: 4,166] | | |

(a)Based on the summer installed generating capacity included in MISO’s resource adequacy process for the planning period from June [removed: 2024] [added: 2025] through May [removed: 2025,] [added: 2026,] except for wind facilities, solar facilities and energy storage, which are based on nameplate capacity.

[removed: (e)Represents] [added: (f)Represents] IPL’s 4% ownership interest, which is operated by MidAmerican Energy Company.

[removed: (f)Represents] [added: (g)Represents] WPL’s 56.6% ownership interest, which is operated by WPL.

[removed: (g)Represents] [added: (h)Represents] Units 2 and 3, which WPL owns.

[removed: (h)Represents] [added: (i)Represents] WPL’s 42.64% ownership interest, which is operated by Invenergy Services, LLC.

[removed: (i)Represents] [added: (j)Represents] WPL’s 53.5% ownership interest, which is operated by WPL.

[added: Other -] Refer to [Note](#i1fc9d0e18c654199a6dadea9bc41997a_292) [9](#i1fc9d0e18c654199a6dadea9bc41997a_292) for information regarding WPL’s lease of the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business.

Corporate Services - Corporate Services’ property included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, [removed: 2024] [added: 2025] consisted primarily of computer software, and the corporate headquarters building located in Madison, Wisconsin.

AEF - AEF’s principal properties included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, [removed: 2024] [added: 2025] were as follows:

The summer installed generating capacity included in MISO’s resource adequacy process for the planning period from June [removed: 2024] [added: 2025] through May [removed: 2025] [added: 2026] for the Sheboygan Falls Energy Facility was 298 MW.

| Wever; Lee Co., IA | | | | | | | | | | | | 2025 | | | | | | | | | | | | | | | | | | 99 | | |

| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

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| Grant County, Grant Co., WI | | | | | | | | | | | | 2025 | | | | | | | | | | | | | | | | | | 100 | | |

| Wood County, Wood Co., WI | | | | | | | | | | | | 2025 | | | | | | | | | | | | | | | | | | 75 | | |

| Total Energy Storage | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 184 | | |

(e)Subsequent to December 31, 2025, IPL retired Prairie Creek Unit 1 and fuel switched Prairie Creek Unit 3 to natural gas.

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| | | | 24 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

Other - IPL’s other property includes steam service assets.

| Name | | | | | | Age as of Filing Date | | | | | | [removed: Registrant] | | | | | | Positions | | |

| Lisa M. Barton | | | | | | [removed: 59] [added: 60] | | | | | | [removed: Alliant Energy] | | | | | | Ms. Barton has served as President and Chief Executive Officer (CEO) and as a director since January 2024. She previously served as President and Chief Operating Officer (COO) since February 2023, as Executive Vice President (VP) and COO of American Electric Power Company, Inc. (AEP) from January 2021 to November 2022, and as Executive VP - Utilities of AEP from January 2020 to December 2020. | | |

| Robert J. Durian | | | | | | [removed: 54] [added: 55] | | | | | | [removed: Alliant Energy, IPL and WPL] | | | | | | Mr. Durian has served as Executive VP and Chief Financial Officer (CFO) since February 2020. He previously served as Senior VP and CFO since February 2019. | | |

| David A. de Leon | | | | | | [removed: 62] [added: 63] | | | | | | [removed: Alliant Energy and IPL] | | | | | | Mr. de Leon has served as Senior VP since January 2019. | | |

| Mayuri N. Farlinger | | | | | | [removed: 42] [added: 43] | | | | | | [removed: Alliant Energy and WPL] | | | | | | Ms. Farlinger has served as [removed: Vice President] [added: VP] since January 2022. She previously served as Director of Operations from January 2020 to December 2021. | | |

| Raja Sundararajan | | | | | | [removed: 49] [added: 50] | | | | | | [removed: Alliant Energy, IPL and WPL] | | | | | | Mr. Sundararajan has served as Executive VP [added: and Chief Strategy Officer] since [added: January 2026. He previously served as Executive VP since] June 2023. He previously served as Executive VP - External Affairs of AEP since July 2022, as Senior VP - Regulatory and Customer Solutions of AEP from July 2021 to July 2022, and as President and COO of AEP Ohio from January 2019 to July 2021. | | |

| Dylan M. Syse | | | | | | [removed: 39] [added: 40] | | | | | | [removed: Alliant Energy, IPL and WPL] | | | | | | Mr. Syse [removed: was selected to become] [added: has served as] Chief Accounting Officer and Controller [removed: effective] [added: since] March [removed: 2,] 2025. He [removed: has] [added: previously] served as Assistant Controller since November 2021, as Manager - Accounting and Reporting from May 2020 to November 2021, and as Manager - Accounting from May 2018 to April 2020. | | |

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| | | | 27 | | | | | |

| | | | | | | | | | | | | | | | | | | | | |

| Name | | | | | | Age as of Filing Date | | | | | | | | | | | | Positions | | |

| Antonio P. Smyth | | | | | | 50 | | | | | | | | | | | | Mr. Smyth has served as Executive VP of Power Generation and Gas Strategy since April 2025. He previously served as Executive VP - Grid Solutions of AEP since December 2024, Executive VP - Grid Solutions & Government Affairs of AEP from April 2023 to December 2024, Senior VP - Grid Solutions of AEP from January 2021 to April 2023, and Senior VP - Transmission Ventures, Strategy & Policy of AEP from October 2018 to December 2020. | | |

| Rebecca C. Valcq | | | | | | 50 | | | | | | | | | | | | Ms. Valcq has served as VP since January 2026. She previously served as Assistant Vice President since 2024. From 2019 to 2024, she served as Chair of the Public Service Commission of Wisconsin. | | |

| | | | | | | | | | | | | | | | | | | | | |

| | | | | | | | | | | | | IPL and WPL | | | | | | Ms. Barton has served as CEO since February 2023, and as a director since January 2024. | | |

| | | | | | | | | | | | | WPL | | | | | | Mr. de Leon has served as President since January 2019. | | |

| | | | | | | | | | | | | IPL | | | | | | Ms. Farlinger has served as President since May 2024. | | |

| | | | 26 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

| Benjamin M. Bilitz | | | | | | 50 | | | | | | Alliant Energy, IPL and WPL | | | | | | Mr. Bilitz has served as Chief Accounting Officer and Controller since December 2016. | | |

Common Stock Data - Alliant Energy’s common stock trades on the Nasdaq Global Select Market under the symbol “LNT,” and the closing sales price at December 31, [removed: 2024] [added: 2025] was [removed: $59.14.][added: $65.01.]

Shareowners - At December 31, [removed: 2024,] [added: 2025,] there were [removed: 19,293] [added: 18,130] holders of record of Alliant Energy’s common stock, including holders through Alliant Energy’s Shareowner Direct Plan.

Dividends - In [removed: October 2024,] [added: November 2025,] Alliant Energy announced an increase in its targeted [removed: 2025] [added: 2026] annual common stock dividend to [removed: $2.03] [added: $2.14] per share, which is equivalent to a quarterly rate of [removed: $0.5075] [added: $0.535] per share, beginning with the February [removed: 2025] [added: 2026] dividend payment.

Common Stock Repurchases - A summary of Alliant Energy common stock repurchases for the quarter ended December 31, [removed: 2024] [added: 2025] was as follows:

| October 1 to October 31 | | | | | | 5,449 | | | | | | $67.76 | | | | | | — | | | | | | N/A | | |

| November 1 to November 30 | | | | | | 2,723 | | | | | | 68.10 | | | | | | — | | | | | | N/A | | |

| December 1 to December 31 | | | | | | 48 | | | | | | 66.30 | | | | | | — | | | | | | N/A | | |

| | | | | | | 8,220 | | | | | | 67.86 | | | | | | — | | | | | | | | |

| October 1 to October 31 | | | | | | 6,487 | | | | | | $59.67 | | | | | | — | | | | | | N/A | | |

| November 1 to November 30 | | | | | | 2,933 | | | | | | 62.65 | | | | | | — | | | | | | N/A | | |

| December 1 to December 31 | | | | | | 19 | | | | | | 59.99 | | | | | | — | | | | | | N/A | | |

| | | | | | | 9,439 | | | | | | 60.60 | | | | | | — | | | | | | | | |

We have audited the accompanying consolidated balance sheets of Alliant Energy Corporation and subsidiaries (the “Company”) as of December 31, [removed: 2024] [added: 2025] and [removed: 2023,] [added: 2024,] the related consolidated statements of income, equity, and cash flows, for each of the three years in the period ended December 31, [removed: 2024,] [added: 2025,] and the related notes and the [removed: schedules] [added: schedule] listed in the Index at Item 15 (collectively referred to as the “financial statements”).

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, [removed: 2024] [added: 2025] and [removed: 2023,] [added: 2024,] and the results of its operations and its cash flows for each of the three years in the period ended December 31, [removed: 2024,] [added: 2025,] in conformity with accounting principles generally accepted in the United States of America.

We have also 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, [removed: 2024,] [added: 2025,] based on criteria established in *Internal Control - Integrated Framework (2013)* issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February [removed: 21, 2025,] [added: 20, 2026,] expressed an unqualified opinion on the Company’s internal control over financial reporting.

Regulatory Accounting - Impact of rate regulation on the financial statements - Refer to Notes 1, 2, and [removed: 3] [added: 11] to the financial statements

[removed: February 21, 2025][added: | 2025: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |]

| | | | [removed: 2024] [added: 2025] | | | | | | [removed: 2023] [added: 2024] | | | | | | [removed: 2022] [added: 2023] | | |

| Electric utility | | | [removed: $3,372] [added: $3,697] | | | | | | [removed: $3,345] [added: $3,372] | | | | | | [removed: $3,421] [added: $3,345] | | |

| Gas utility | | | [removed: 465] [added: 525] | | | | | | [removed: 540] [added: 465] | | | | | | [removed: 642] [added: 540] | | |

| Other utility | | | [removed: 54] [added: 51] | | | | | | [removed: 52] [added: 54] | | | | | | [removed: 49] [added: 52] | | |

| Non-utility | | | [removed: 90] [added: 89] | | | | | | 90 | | | | | | [removed: 93] [added: 90] | | |

| Total revenues | | | [removed: 3,981] [added: 4,362] | | | | | | [removed: 4,027] [added: 3,981] | | | | | | [removed: 4,205] [added: 4,027] | | |

| Electric production fuel and purchased power | | | [removed: 628] [added: 742] | | | | | | [removed: 736] [added: 628] | | | | | | [removed: 830] [added: 736] | | |

| Electric transmission service | | | [removed: 613] [added: 625] | | | | | | [removed: 583] [added: 613] | | | | | | [removed: 573] [added: 583] | | |

| Cost of gas sold | | | [removed: 224] [added: 263] | | | | | | [removed: 299] [added: 224] | | | | | | [removed: 389] [added: 299] | | |

| Asset valuation charge for IPL’s Lansing Generating Station | | | [removed: 60] [added: —] | | | | | | [removed: —] [added: 60] | | | | | | — | | |

| Other | | | [removed: 676] [added: 740] | | | | | | [removed: 675] [added: 676] | | | | | | [removed: 704] [added: 675] | | |

| Depreciation and amortization | | | [removed: 772] [added: 846] | | | | | | [removed: 676] [added: 772] | | | | | | [removed: 671] [added: 676] | | |

| Taxes other than income taxes | | | [removed: 122] [added: 121] | | | | | | [removed: 115] [added: 122] | | | | | | [removed: 110] [added: 115] | | |

| Total operating expenses | | | [removed: 3,095] [added: 3,337] | | | | | | [removed: 3,084] [added: 3,095] | | | | | | [removed: 3,277] [added: 3,084] | | |

| Operating income | | | [removed: 886] [added: 1,025] | | | | | | [removed: 943] [added: 886] | | | | | | [removed: 928] [added: 943] | | |

| Interest expense | | | [removed: 449] [added: 512] | | | | | | [removed: 394] [added: 449] | | | | | | [removed: 325] [added: 394] | | |

| Equity income from unconsolidated investments, net | | | [removed: (61)] [added: (60)] | | | | | | (61) | | | | | | [removed: (51)] [added: (61)] | | |

| Allowance for funds used during construction | | | [removed: (75)] [added: (89)] | | | | | | [removed: (100)] [added: (75)] | | | | | | [removed: (60)] [added: (100)] | | |

| Other | | | [removed: (3)] [added: 1] | | | | | | [removed: 3] [added: (3)] | | | | | | [removed: 6] [added: 3] | | |

| Total other (income) and deductions | | | [removed: 310] [added: 364] | | | | | | [removed: 236] [added: 310] | | | | | | [removed: 220] [added: 236] | | |

| Income before income taxes | | | [removed: 576] [added: 661] | | | | | | [removed: 707] [added: 576] | | | | | | [removed: 708] [added: 707] | | |

| Income tax expense (benefit) | | | [removed: (114)] [added: (149)] | | | | | | [removed: 4] [added: (114)] | | | | | | [removed: 22] [added: 4] | | |

| Net income attributable to Alliant Energy common shareowners | | | [removed: $690] [added: $810] | | | | | | [removed: $703] [added: $690] | | | | | | [removed: $686] [added: $703] | | |

| Basic | | | [removed: 256.5] [added: 257.0] | | | | | | [removed: 253.0] [added: 256.5] | | | | | | [removed: 250.9] [added: 253.0] | | |

| Diluted | | | [removed: 256.8] [added: 257.8] | | | | | | [removed: 253.3] [added: 256.8] | | | | | | [removed: 251.2] [added: 253.3] | | |

| Earnings per weighted average common share attributable to Alliant Energy common [removed: shareowners (basic and diluted)] [added: shareowners:] | | | [removed: $2.69] | | | | | | [removed: $2.78] | | | | | | [removed: $2.73] | | |

| | | | [removed: 2024] [added: 2025] | | | | | | [added: 2024 | | | | | |] 2023 | | |

| Cash and cash equivalents | | | [removed: $81] [added: $556] | | | | | | [removed: $62] [added: $81] | | |

| Accounts receivable, less allowance for expected credit losses | | | [removed: 427] [added: 476] | | | | | | [removed: 475] [added: 427] | | |

| Production fuel, at weighted average cost | | | [removed: 54] [added: 46] | | | | | | [removed: 62] [added: 54] | | |

| Gas stored underground, at weighted average cost | | | [removed: 55] [added: 49] | | | | | | [removed: 79] [added: 55] | | |

| Materials and supplies, at weighted average cost | | | [removed: 186] [added: 193] | | | | | | [removed: 202] [added: 186] | | |

| Regulatory assets | | | [removed: 210] [added: 155] | | | | | | [removed: 232] [added: 210] | | |

| Other | | | [removed: 171] [added: 222] | | | | | | [removed: 160] [added: 171] | | |

| Total current assets | | | [removed: 1,184] [added: 1,697] | | | | | | [removed: 1,272] [added: 1,184] | | |

- We obtained representation from management asserting that regulatory assets recorded in the financial statements are probable of recovery and that obligations to make refunds to customers are appropriately recorded as regulatory liabilities.

February 20, 2026

| Basic | | | $3.15 | | | | | | $2.69 | | | | | | $2.78 | | |

| Diluted | | | $3.14 | | | | | | $2.69 | | | | | | $2.78 | | |

| Accrued interest | | | 124 | | | | | | 112 | | |

| Other | | | 251 | | | | | | 273 | | |

| Depreciation and amortization | | | 846 | | | | | | 772 | | | | | | 676 | | |

| Federal (a) | | | $271 | | | | | | $202 | | | | | | $82 | | |

| State - Iowa | | | (5) | | | | | | (5) | | | | | | 6 | | |

| Ending balance | | | $3 | | | | | | $3,101 | | | | | | $4,243 | | | | | | $1 | | | | | | ($14) | | | | | | | | | | | | | | | | | | $7,334 | | |

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.

- We obtained representation from management asserting that regulatory assets recorded in the financial statements are probable of recovery and that obligations to make refunds to customers are appropriately recorded as regulatory liabilities.

February 20, 2026

| Asset valuation charge for IPL’s Lansing Generating Station | | | — | | | | | | 60 | | | | | | — | | |

| | | | 2025 | | | | | | 2024 | | |

| Depreciation and amortization | | | 463 | | | | | | 404 | | | | | | 388 | | |

| Asset valuation charge for IPL’s Lansing Generating Station | | | — | | | | | | 60 | | | | | | — | | |

| Cash receipts on sold receivables | | | 628 | | | | | | 593 | | | | | | 453 | | |

| Federal (a) | | | $142 | | | | | | $164 | | | | | | $98 | | |

| State - Iowa | | | (3) | | | | | | 11 | | | | | | 19 | | |

| Beneficial interest obtained in exchange for securitized accounts receivable | | | $126 | | | | | | $163 | | | | | | $216 | | |

| 2025: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

| Capital contributions from parent | | | | | | | | | 285 | | | | | | | | | | | | | | | | | | 285 | | |

| Ending balance | | | $33 | | | | | | $3,497 | | | | | | $1,314 | | | | | | | | | | | | $4,844 | | |

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.

Regulatory Accounting - Impact of rate regulation on the financial statements - Refer to Notes 1, 2, and 11 to the financial statements

- We obtained representation from management asserting that regulatory assets recorded in the financial statements are probable of recovery and that obligations to make refunds to customers are appropriately recorded as regulatory liabilities.

February 20, 2026

| | | | 2025 | | | | | | 2024 | | |

| Depreciation and amortization | | | 370 | | | | | | 357 | | | | | | 280 | | |

| Other | | | (63) | | | | | | (51) | | | | | | (47) | | |

| Accounts receivable | | | (56) | | | | | | (5) | | | | | | 23 | | |

| Other | | | (19) | | | | | | — | | | | | | 18 | | |

| Proceeds from sales of partial ownership interests in West Riverside | | | — | | | | | | 123 | | | | | | 120 | | |

| Other | | | (23) | | | | | | (19) | | | | | | (47) | | |

| Other | | | (9) | | | | | | (14) | | | | | | (16) | | |

| Income taxes, net: | | | | | | | | | | | | | | | | | |

| Federal (a) | | | $124 | | | | | | $41 | | | | | | ($25) | | |

| State - Wisconsin | | | (15) | | | | | | (27) | | | | | | (25) | | |

| 2025: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

| | | | 46 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

| | | | 47 | | | | | |

- We inspected minutes of the board of directors and other committees of the Company, regulatory orders and other filings with the regulatory agencies to identify evidence that may contradict management’s assertion regarding probability of abandonment or that may have an impact on the recorded balances.

| | | | | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |

| Other | | | 385 | | | | | | 302 | | |

| 2022: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

| Beginning balance | | | $3 | | | | | | $2,749 | | | | | | $3,250 | | | | | | $— | | | | | | ($12) | | | | | | | | | | | | | | | | | | $5,990 | | |

| 2022: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

| Ending balance | | | 33 | | | | | | 2,807 | | | | | | 968 | | | | | | | | | | | | 3,808 | | |

| Accounts payable | | | 209 | | | | | | 293 | | |

| Equity component of allowance for funds used during construction | | | (23) | | | | | | (59) | | | | | | (36) | | |

| Other | | | (28) | | | | | | 12 | | | | | | 25 | | |

| Regulatory assets | | | 72 | | | | | | (34) | | | | | | (163) | | |

| Accounts payable | | | 50 | | | | | | (57) | | | | | | 22 | | |

| Other | | | (62) | | | | | | 33 | | | | | | (141) | | |

| Other | | | (19) | | | | | | (47) | | | | | | (13) | | |

| Payments to retire long-term debt | | | — | | | | | | — | | | | | | (250) | | |

| Other | | | (14) | | | | | | (16) | | | | | | (9) | | |

| Beginning balance | | | $66 | | | | | | $1,704 | | | | | | $1,053 | | | | | | | | | | | | $2,823 | | |

| Other | | | | | | | | | (1) | | | | | | | | | | | | | | | | | | (1) | | |

The Inflation Reduction Act of 2022 provides the ability to transfer renewable tax credits to other corporate taxpayers.

For renewable tax credits subject to future transfer, a valuation allowance is recorded for the difference between the tax value of the credits and the expected sales price.

Refer to Notes [1](#i1fc9d0e18c654199a6dadea9bc41997a_298)[1](#i1fc9d0e18c654199a6dadea9bc41997a_298) and [1](#i1fc9d0e18c654199a6dadea9bc41997a_340)[6](#i1fc9d0e18c654199a6dadea9bc41997a_340)[(d)](#i1fc9d0e18c654199a6dadea9bc41997a_340) for further discussion of the transfer of renewable tax credits to other corporate taxpayers, including related valuation allowances and indemnification requirements, respectively.

In October 2024, the IUC issued an order approving the implementation of updated depreciation rates for IPL effective October 1, 2024.

IPL estimates the new average rates of depreciation for its electric generation and electric distribution properties will be approximately 3.8% and 3.0%, respectively, during 2025.

All other finance lease assets are depreciated on a straight-line basis over the shorter of the useful life of the underlying asset or the lease term.

| IPL’s DAEC PPA amendment | | | 18 | | | | | | 42 | | | | | | 18 | | | | | | 42 | | | | | | — | | | | | | — | | |

| Other | | | 150 | | | | | | 159 | | | | | | 56 | | | | | | 50 | | | | | | 94 | | | | | | 109 | | |

| | | | $2,274 | | | | | | $2,261 | | | | | | $1,586 | | | | | | $1,577 | | | | | | $688 | | | | | | $684 | | |

Refer to [Note 1](#i1fc9d0e18c654199a6dadea9bc41997a_316)[4](#i1fc9d0e18c654199a6dadea9bc41997a_316) for discussion of changes in Alliant Energy’s, IPL’s and WPL’s derivative liabilities/assets during 2024, which resulted in comparable changes to regulatory assets/liabilities on the balance sheets.

IPL’s DAEC PPA Amendment - In 2020, IPL made a buyout payment of $110 million in exchange for shortening the term of its DAEC PPA by 5 years.

The buyout payment, including a return on, is being recovered from IPL’s retail and wholesale customers from 2021 through 2025, and is currently being amortized to “Electric production fuel and purchased power” in Alliant Energy’s and IPL’s income statements.

| Commodity cost recovery | | | 17 | | | | | | 48 | | | | | | 12 | | | | | | 13 | | | | | | 5 | | | | | | 35 | | |

| Other | | | 29 | | | | | | 85 | | | | | | 14 | | | | | | 56 | | | | | | 15 | | | | | | 29 | | |

| | | | $1,028 | | | | | | $1,130 | | | | | | $546 | | | | | | $644 | | | | | | $482 | | | | | | $486 | | |

A majority of these benefits will be addressed in a future regulatory proceeding, with a portion of the benefits passed on to WPL’s electric customers in 2024 and 2025.

WPL’s Retail Fuel-related Rate Filing (2021 Forward-looking Test Period) \- In 2023, WPL collected $37 million, plus interest, from its retail electric customers related to actual fuel-related costs for 2021 that were higher than fuel-related costs used to determine rates for such period.

| Generation in service (a)(b) | | | $11,156 | | | | | | $9,180 | | | | | | $5,924 | | | | | | $5,025 | | | | | | $5,232 | | | | | | $4,155 | | |

| | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- |

| | | | 106 | | | | | |

Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s Chief Executive Officer, Chief Financial Officer and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures [removed: as] [added: (as defined in Rule 13a-15(e)] of the [removed: end] [added: Securities Exchange Act] of [removed: the quarter ended] [added: 1934, as amended) as of] December 31, [removed: 2024] [added: 2025] pursuant to the requirements of the Securities Exchange Act of 1934, as amended.

Based on their evaluation, the Chief Executive Officer and the Chief Financial Officer concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the [removed: end of the] quarter ended December 31, [removed: 2024.][added: 2025.]

There was no change in Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting that occurred during the quarter ended December 31, [removed: 2024] [added: 2025] that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s, IPL’s [removed: and] [added: or] WPL’s internal control over financial reporting.

Alliant Energy’s, IPL’s and WPL’s management assessed the effectiveness of their respective internal control over financial reporting as of December 31, [removed: 2024] [added: 2025] using the criteria set forth in *Internal Control - Integrated Framework (2013)* issued by the Committee of Sponsoring Organizations of the Treadway Commission.

Based on these assessments, Alliant Energy’s, IPL’s and WPL’s management concluded that, as of December 31, [removed: 2024,] [added: 2025,] their respective internal control over financial reporting was effective.

We have audited the internal control over financial reporting of Alliant Energy Corporation and subsidiaries (the “Company”) as of December 31, [removed: 2024,] [added: 2025,] based on criteria established in *Internal Control - Integrated Framework (2013)* issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, [removed: 2024,] [added: 2025,] based on criteria established in *Internal Control - Integrated Framework (2013)* issued by COSO.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated financial statements as of and for the year ended December 31, [removed: 2024,] [added: 2025,] of the Company and our report dated February [removed: 21, 2025,] [added: 20, 2026,] expressed an unqualified opinion on the Company’s [removed: 2024] [added: 2025] financial statements.

| | | | 107 | | | | | |

February 20, 2026

| | | | 108 | | | | | |

| | | | 102 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

February 21, 2025

| | | | 103 | | | | | |

During the quarter ended December 31, [removed: 2024,] [added: 2025,] no director or officer of Alliant Energy, IPL or WPL adopted or terminated a Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement, as each term is defined in Item 408(a) of Regulation S-K.

The information required by Item 10 relating to directors and nominees for election of directors at the [removed: 2025] [added: 2026] Annual Meeting of Shareowners, the timely filing of reports under Section 16 of the Securities Exchange Act of 1934, audit committees and audit committee financial experts, insider trading policies and procedures, and Alliant [removed: Energy’s, IPL’s and WPL’s] [added: Energy’s] Code of Conduct is incorporated herein by reference to the relevant information in the [removed: 2025] [added: 2026] Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant [removed: Energy’s, IPL’s and WPL’s] [added: Energy’s] fiscal [removed: years.][added: year.]

Information regarding executive officers of Alliant [removed: Energy, IPL and WPL] [added: Energy] may be found in Part I of this report under the caption “[Information About Executive Officers](#i1fc9d0e18c654199a6dadea9bc41997a_79).”

IPL and WPL are omitted pursuant to Instruction I(2)(c).

The directors of Alliant Energy, IPL and WPL are the same, and therefore, the information required by Item 10 relating to directors and nominees for election of directors is the same for all registrants.

The code of ethics, also referred to as the Code of Conduct, of Alliant Energy, IPL and WPL are the same.

[removed: Therefore, the] [added: The] information required by Item 11 for [removed: each of] Alliant [removed: Energy, IPL and WPL] [added: Energy] is incorporated herein by reference to the relevant information in the [removed: 2025] [added: 2026] Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant [removed: Energy’s, IPL’s and WPL’s] [added: Energy’s] fiscal [removed: years.][added: year.]

IPL and WPL are omitted pursuant to Instruction I(2)(c).

The directors and executive officers of Alliant Energy, IPL and WPL for which compensation information must be included are the same.

Information regarding Alliant Energy’s equity compensation plans as of December 31, [removed: 2024] [added: 2025] was as follows:

| Equity compensation plans [added: not] approved by shareowners [added: (d)] | | | | | | [removed: 1,529,346 (a)] [added: N/A] | | | | | | [removed: $51.63] [added: N/A] | | | | | | [removed: 7,107,084 (b)] [added: N/A (e)] | | |

| Equity compensation plans [removed: not] approved by shareowners [removed: (c)] | | | | | | [removed: N/A] [added: 1,686,388 (a)] | | | | | | N/A [added: (b)] | | | | | | [removed: N/A (d)] [added: 6,785,563 (c)] | | |

[removed: (b)All] [added: (c)All] of the available shares under the 2020 OIP may be issued as awards in the form of shares of Alliant Energy’s common stock, restricted stock, restricted stock units, performance shares, performance units and other stock-based or cash-based awards.

As of December 31, [removed: 2024,] [added: 2025,] there were performance shares and restricted stock units outstanding under the 2020 OIP, the only plan under which such equity awards are currently granted.

[removed: (c)As] [added: (d)As] of December 31, [removed: 2024,] [added: 2025,] there were [removed: 372,116] [added: 367,338] shares of Alliant Energy’s common stock held under the DCP, which is described in [Note 1](#i1fc9d0e18c654199a6dadea9bc41997a_310)[2](#i1fc9d0e18c654199a6dadea9bc41997a_310)[(c)](#i1fc9d0e18c654199a6dadea9bc41997a_310).

[removed: (d)There] [added: (e)There] is no limit on the number of shares of Alliant Energy’s common stock that may be held under the DCP.

The remainder of the information required by Item 12 for Alliant [removed: Energy, and the information required by Item 12 for each of IPL and WPL,] [added: Energy] is incorporated herein by reference to the relevant information in the [removed: 2025] [added: 2026] Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant [removed: Energy’s, IPL’s and WPL’s] [added: Energy’s] fiscal year.

| | | | | | | 1,686,388 | | | | | | N/A | | | | | | 6,785,563 | | |

(b)No cash consideration is received when shares are distributed for earned performance shares and restricted stock units.

Accordingly, there is no weighted-average exercise price.

IPL and WPL are omitted pursuant to Instruction I(2)(c).

| | | | 109 | | | | | |

| | | | | | | 1,529,346 | | | | | | $51.63 | | | | | | 7,107,084 | | |

| | | | 104 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

The information required by Item 13 for [removed: each of] Alliant [removed: Energy, IPL and WPL] [added: Energy] is incorporated herein by reference to the relevant information in the [removed: 2025] [added: 2026] Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant [removed: Energy’s, IPL’s and WPL’s] [added: Energy’s] fiscal [removed: years.][added: year.]

IPL and WPL are omitted pursuant to Instruction I(2)(c).

The information required by Item 14 is incorporated herein by reference to the relevant information in the [removed: 2025] [added: 2026] Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s fiscal year.

| Audit fees | | | [removed: $1,412] [added: $1,479] | | | | | | 96% | | | | | | [removed: $1,468] [added: $1,412] | | | | | | [removed: 95%] [added: 96%] | | | | | | [removed: $1,242] [added: $1,294] | | | | | | [removed: 92%] [added: 90%] | | | | | | [removed: $1,228] [added: $1,242] | | | | | | 92% | | |

| Audit-related fees | | | [removed: 59] [added: 61] | | | | | | 4% | | | | | | [removed: 57] [added: 59] | | | | | | 4% | | | | | | [removed: 103] [added: 137] | | | | | | [removed: 8%] [added: 10%] | | | | | | 103 | | | | | | 8% | | |

| Tax fees | | | [removed: 3] [added: 4] | | | | | | —% | | | | | | [removed: 8] [added: 3] | | | | | | [removed: 1%] [added: —%] | | | | | | [removed: 3] [added: 4] | | | | | | —% | | | | | | [removed: 7] [added: 3] | | | | | | —% | | |

| All other fees | | | [removed: 3] [added: 2] | | | | | | —% | | | | | | [removed: 4] [added: 3] | | | | | | —% | | | | | | 2 | | | | | | —% | | | | | | [removed: 4] [added: 2] | | | | | | —% | | |

| | | | [removed: $1,477] [added: $1,546] | | | | | | 100% | | | | | | [removed: $1,537] [added: $1,477] | | | | | | 100% | | | | | | [removed: $1,350] [added: $1,437] | | | | | | 100% | | | | | | [removed: $1,342] [added: $1,350] | | | | | | 100% | | |

IPL’s and WPL’s audit fees for [removed: 2024] [added: 2025] and [removed: 2023] [added: 2024] consisted of the respective fees billed for the audits of the financial statements of IPL and its subsidiaries and WPL and its subsidiaries, for reviews of financial statements included in Form 10-Q filings, and for services normally provided in connection with statutory and regulatory filings, such as financing transactions.

IPL’s and WPL’s audit fees also included their respective portion of fees for the [removed: 2024] [added: 2025] and [removed: 2023] [added: 2024] audits of Alliant Energy’s financial statements and effectiveness of internal controls over financial reporting.

IPL’s and WPL’s audit-related fees for [removed: 2024] [added: 2025] and [removed: 2023] [added: 2024] consisted of the fees billed for services rendered related to employee benefits plan [removed: audits and] [added: audits,] other attest [removed: services.][added: services and WPL’s audit-related fees for 2025 also included an audit of expenditures of federal awards for the Department of Energy.]

All other fees for [removed: 2024] [added: 2025] and [removed: 2023] [added: 2024] for IPL and WPL consisted of license fees for accounting research software products and seminars.

| | | | 2025 | | | | | | | | | | | | 2024 | | | | | | | | | | | | 2025 | | | | | | | | | | | | 2024 | | | | | | | | |

IPL’s and WPL’s tax fees for 2025 and 2024 consisted of the fees billed for professional services rendered for tax compliance.

| | | | 2024 | | | | | | | | | | | | 2023 | | | | | | | | | | | | 2024 | | | | | | | | | | | | 2023 | | | | | | | | |

IPL’s and WPL’s tax fees for 2024 consisted of the fees billed for professional services rendered for tax compliance, and 2023 consisted of the fees billed for professional services rendered for tax compliance, tax advice and tax planning, including all services performed by the tax professional staff of affiliates of the independent registered public accounting firm, except those rendered in connection with the audit.

| CONDENSED STATEMENTS OF INCOME | | | [removed: 2024] [added: 2025] | | | | | | [removed: 2023] [added: 2024] | | | | | | [removed: 2022] [added: 2023] | | |

| Operating expenses | | | [removed: $3] [added: $4] | | | | | | $3 | | | | | | [removed: $9] [added: $3] | | |

| Operating loss | | | [removed: (3)] [added: (4)] | | | | | | (3) | | | | | | [removed: (9)] [added: (3)] | | |

| Equity earnings from consolidated subsidiaries | | | [removed: (734)] [added: (863)] | | | | | | [removed: (742)] [added: (734)] | | | | | | [removed: (707)] [added: (742)] | | |

| Interest expense | | | [removed: 40] [added: 57] | | | | | | [removed: 34] [added: 40] | | | | | | [removed: 6] [added: 34] | | |

| Other | | | [removed: 5] [added: (3)] | | | | | | [removed: 4] [added: 5] | | | | | | [removed: 1] [added: 4] | | |

| Total other (income) and deductions | | | [removed: (689)] [added: (809)] | | | | | | [removed: (704)] [added: (689)] | | | | | | [removed: (700)] [added: (704)] | | |

| Income before income taxes | | | [removed: 686] [added: 805] | | | | | | [removed: 701] [added: 686] | | | | | | [removed: 691] [added: 701] | | |

| Income tax [removed: expense (benefit)] [added: benefit] | | | [removed: (3)] [added: (6)] | | | | | | [removed: (5)] [added: (3)] | | | | | | [removed: 2] [added: (5)] | | |

| Net income | | | [removed: $689] [added: $811] | | | | | | [removed: $706] [added: $689] | | | | | | [removed: $689] [added: $706] | | |

| CONDENSED BALANCE SHEETS | | | [removed: 2024] [added: 2025] | | | | | | [removed: 2023] [added: 2024] | | |

| Notes receivable from affiliated companies | | | [removed: $103] [added: 114] | | | | | | [removed: $96] [added: 103] | | |

| Income tax refunds receivable | | | 12 | | | | | | [removed: —] [added: 12] | | |

| Other | | | [removed: 2] [added: 6] | | | | | | [removed: 1] [added: 2] | | |

| Total current assets | | | [removed: 117] [added: 644] | | | | | | [removed: 97] [added: 117] | | |

| Investments in consolidated subsidiaries | | | [removed: 9,123] [added: 9,784] | | | | | | [removed: 8,405] [added: 9,123] | | |

| Other | | | 1 | | | | | | [removed: 2] [added: 1] | | |

| Total investments | | | [removed: 9,124] [added: 9,785] | | | | | | [removed: 8,407] [added: 9,124] | | |

| Other assets | | | [removed: 84] [added: 102] | | | | | | [removed: 90] [added: 84] | | |

| Total assets | | | [removed: $9,325] [added: $10,531] | | | | | | [removed: $8,594] [added: $9,325] | | |

| Current maturities of long-term debt | | | [removed: $571] [added: $574] | | | | | | [removed: $—] [added: $571] | | |

| Commercial paper | | | [removed: 325] [added: —] | | | | | | [removed: 157] [added: 325] | | |

| Notes payable to affiliated companies | | | [removed: 1,401] [added: 1,300] | | | | | | [removed: 1,068] [added: 1,401] | | |

| Other | | | [removed: 10] [added: 21] | | | | | | 10 | | |

| Total current liabilities | | | [removed: 2,307] [added: 1,895] | | | | | | [removed: 1,235] [added: 2,307] | | |

| Long-term debt, net (excluding current portion) | | | [removed: —] [added: 1,286] | | | | | | [removed: 568] [added: —] | | |

| Other liabilities | | | [removed: 3] [added: 4] | | | | | | [removed: 2] [added: 3] | | |

| Common stock and additional paid-in capital | | | [removed: 3,063] [added: 3,104] | | | | | | [removed: 3,033] [added: 3,063] | | |

| Retained earnings | | | [removed: 3,965] [added: 4,255] | | | | | | [removed: 3,768] [added: 3,965] | | |

| Shares in deferred compensation trust | | | (14) | | | | | | [removed: (13)] [added: (14)] | | |

| Total common equity | | | [removed: 7,015] [added: 7,346] | | | | | | [removed: 6,789] [added: 7,015] | | |

| Total liabilities and equity | | | [removed: $9,325] [added: $10,531] | | | | | | [removed: $8,594] [added: $9,325] | | |

| CONDENSED STATEMENTS OF CASH FLOWS | | | [removed: 2024] [added: 2025] | | | | | | [removed: 2023] [added: 2024] | | | | | | [removed: 2022] [added: 2023] | | |

| Net cash flows from operating activities | | | [removed: $355] [added: $529] | | | | | | [removed: $445] [added: $355] | | | | | | [removed: $492] [added: $445] | | |

| Capital contributions to consolidated subsidiaries | | | [removed: (380)] [added: (365)] | | | | | | [removed: (325)] [added: (380)] | | | | | | [removed: (530)] [added: (325)] | | |

| Net change in notes receivable from and payable to affiliates | | | [removed: 326] [added: (113)] | | | | | | [removed: (281)] [added: 326] | | | | | | [removed: 369] [added: (281)] | | |

| Net cash flows used for investing activities | | | [removed: (54)] [added: (478)] | | | | | | [removed: (606)] [added: (54)] | | | | | | [removed: (161)] [added: (606)] | | |

| Common stock dividends | | | [removed: (492)] [added: (521)] | | | | | | [removed: (456)] [added: (492)] | | | | | | [removed: (428)] [added: (456)] | | |

| Proceeds from issuance of common stock, net | | | 23 | | | | | | [removed: 246] [added: 23] | | | | | | [removed: 25] [added: 246] | | |

| Proceeds from issuance of long-term debt | | | [removed: —] [added: 1,286] | | | | | | [removed: 565] [added: —] | | | | | | [removed: —] [added: 565] | | |

| | | | 110 | | | | | |

| Cash and cash equivalents | | | $512 | | | | | | $— | | |

| | | | 111 | | | | | |

| Income taxes, net: | | | | | | | | | | | | | | | | | |

| Federal | | | $4 | | | | | | $11 | | | | | | $8 | | |

| State - Iowa | | | — | | | | | | (15) | | | | | | (13) | | |

| State - Wisconsin | | | — | | | | | | 12 | | | | | | 27 | | |

| | | | 112 | | | | | |

| 4.1c | | | [Extension and Third Amendment to Amended and Restated Five-Year Master Credit Agreement, effective December 18, 2025, among Alliant Energy, IPL, WPL, Wells Fargo Bank, National Association and the lender parties set forth therein](https://www.sec.gov/Archives/edgar/data/352541/000035254126000007/lnt1231202510-kex41c.htm) | | |

| 4.3 | | | [Indenture, dated as of May 15, 2025, between Alliant Energy and The Bank of New York Mellon Trust Company, N.A., as trustee (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Form 8-K, filed May 15, 2025 (File No. 1-9894))](https://www.sec.gov/Archives/edgar/data/352541/000119312525120808/d928152dex41.htm) | | |

| 4.4 | | | [Indenture, dated as of September 26, 2025, between Alliant Energy and The Bank of New York Mellon Trust Company, N.A., as trustee (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Form 8-K, filed September 26, 2025 (File No. 1-9894))](https://www.sec.gov/Archives/edgar/data/352541/000035254125000076/lnt092320258-kex41.htm) | | |

| 4.4a | | | [First Supplemental Indenture, dated as of September 26, 2025, between Alliant Energy and The Bank of New York Mellon Trust Company, N.A., as trustee, relating to the 5.750% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2056 (incorporated by reference to Exhibit 4.2 to Alliant Energy’s Form 8-K, filed September 26, 2025 (File No. 1-9894))](https://www.sec.gov/Archives/edgar/data/352541/000035254125000076/lnt092320258-kex42.htm) | | |

| | | | 113 | | | | | |

| 4.21 | | | [Officers’ Certificate, dated December 5, 2025, creating WPL’s 5.700% Debentures due 2055 (incorporated by reference to Exhibit 4.1 to WPL’s Form 8-K, filed December 5, 2025 (File No. 0-337))](https://www.sec.gov/Archives/edgar/data/107832/000035254125000085/lnt120220258-kex41.htm) | | |

| | | | 114 | | | | | |

| | | | | | |

| --- | --- | --- | --- | --- | --- |

| Exhibit Number | | | Description | | |

| | | | 105 | | | | | |

[Table of C](#i1fc9d0e18c654199a6dadea9bc41997a_7)[o](#i1fc9d0e18c654199a6dadea9bc41997a_7)[ntents](#i1fc9d0e18c654199a6dadea9bc41997a_7)

| | | | 106 | | | | | |

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

| | | | | | | | | | | | | | | | | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |

| | | | | | | | | | | | | Additions | | | | | | | | | | | |

| | | | | | | | | | Balance, | | | (Charged to | | | | | | | | | Balance, | | |

| Description | | | | | | | | | January 1 | | | Expense) | | | | | | Deductions (a) | | | December 31 | | |

| | | | | | | | | | (in millions) | | | | | | | | | | | | | | |

Valuation and Qualifying Accounts Which are Deducted in the Balance Sheet from the Assets to Which They Apply:

| | | | | | | | | | | | | | | | | | | | | | | | | | | |

| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |

| | | | Accumulated Provision for Uncollectible Accounts: | | | | | | | | | | | | | | | | | | | | | | | |

| | | | | | | Alliant Energy (b) | | | | | | | | | | | | | | | | | | | | |

| | | | | | | | | | Year ended December 31, 2024 | | | $8 | | | $24 | | | | | | $24 | | | $8 | | |

| | | | | | | | | | Year ended December 31, 2023 | | | 7 | | | 20 | | | | | | 19 | | | 8 | | |

| | | | | | | | | | Year ended December 31, 2022 | | | 11 | | | 17 | | | | | | 21 | | | 7 | | |

| | | | | | | IPL (b) | | | | | | | | | | | | | | | | | | | | |

| | | | | | | | | | Year ended December 31, 2024 | | | $— | | | $13 | | | | | | $13 | | | $— | | |

| | | | | | | | | | Year ended December 31, 2023 | | | — | | | 11 | | | | | | 11 | | | — | | |

| | | | | | | | | | Year ended December 31, 2022 | | | 1 | | | 7 | | | | | | 8 | | | — | | |

| | | | | | | WPL | | | | | | | | | | | | | | | | | | | | |

| | | | | | | | | | Year ended December 31, 2024 | | | $8 | | | $11 | | | | | | $11 | | | $8 | | |

| | | | | | | | | | Year ended December 31, 2023 | | | 7 | | | 9 | | | | | | 8 | | | 8 | | |

| | | | | | | | | | Year ended December 31, 2022 | | | 10 | | | 10 | | | | | | 13 | | | 7 | | |

Note: The above provisions relate to various customer, notes and other receivable balances included in various line items on the respective balance sheets.