ALLIANT ENERGY CORP

Mission, Purpose and Strategy

Alliant Energy’s mission is to deliver the energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and responsibly. This mission aligns with Alliant Energy’s purpose - to serve customers and build stronger communities - which guides it through the evolving dynamics of the economy and the energy industry. Alliant Energy leads as a corporate citizen, advancing environmental stewardship and supporting the communities in its service territories. Alliant Energy’s mission and purpose are supported by a strategy focused on meeting evolving customer expectations, delivering attractive returns for investors, and advancing emerging technologies and generation to enable safe, secure and future-ready energy production. This strategy includes the following key elements:

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

Key Highlights -

•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. Alliant Energy’s industry-leading wind and solar energy resources provide zero-fuel cost generation as well as generate renewable tax credits that are provided to its electric customers. 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.

•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 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) for discussion of $285 million, $216 million and $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in 2025, 2024 and 2023, respectively.

•Reductions in Iowa corporate income tax rates resulting from tax reform enacted in 2022 are expected to provide cost benefits to IPL’s electric and gas customers in the future. IPL’s retail electric and gas customers began receiving these benefits with the new base rates effective October 1, 2024.

•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.

•IPL maintaining flat base rates for its retail electric and gas customers from 2021 through September 30, 2024, as well as a retail electric base rate moratorium from October 2025 through September 2029 approved by the IUC in IPL’s most recent retail electric rate review.

•Completion of a restructuring and voluntary employee separation program in 2024, which is expected to reduce operation and maintenance expenses in the future. Refer to Note 12 for discussion of this program.

•IPL and WPL have entered into conditional commitments with the U.S. Department of Energy Office of Energy Dominance Financing, formerly the Loan Programs 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 eligible projects as defined in the governing agreement.

•In July 2024, the U.S. Department of Energy Office of 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.

•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.

Making customer-focused investments -Alliant Energy’s strategic priorities include making customer-focused investments to provide reliable, resilient, and sustainable energy solutions. 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.

Key Highlights (refer to “Customer Investments” for details) -

•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 1,600 MW of new natural gas resources, approximately 1,000 MW of new energy storage, approximately 1,300 MW of new renewable generation, improvements of approximately 410 MW at existing natural gas-fired EGUs, and refurbishments at approximately 450 MW of existing wind farms. Alliant Energy is currently evaluating the impact of potential additional 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.

•Completion of new solar generation at WPL (1,089 MW in Wisconsin from 2022-2024) and IPL (400 MW in Iowa in 2024), and IPL’s refurbishment of the existing Franklin County wind farm in Iowa in 2024.

•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.

•Alliant Energy continues to partner with its commercial and industrial customers in Iowa and Wisconsin to help develop renewable solutions to support their sustainability initiatives.

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

Key Highlights -

•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. The energy resources to serve this expected load are included in the construction and acquisition table in “Liquidity and Capital Resources.” The actual timing and amount of increases in IPL’s 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.

•The IUC’s order for IPL’s most recent retail electric rate review includes the creation of an individual customer rate tariff, allowing IPL to attract new load growth to its service territory. In addition, Iowa’s Major Economic Growth Attraction program and Iowa’s and Wisconsin’s sales and use tax exemption for qualified data centers, encourage economic development in Alliant Energy’s service territory.

•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. A decision from the PSCW is currently expected in the second quarter of 2026.

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

Financial Results Overview -The table below includes diluted EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures. Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance. Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners were as follows (dollars in millions, except per share amounts):

Alliant Energy’s Utilities and Corporate Services net income increased by $153 million in 2025 compared to 2024. The increase was primarily due to 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 review in 2024, restructuring and voluntary separation charges in 2024, and an ARO charge allocated to the steam business at IPL due to the revised CCR Rule in 2024. These items were partially offset by higher other operation and maintenance expenses, depreciation and financing expenses.

Alliant Energy’s Non-utility and Parent net income decreased by $34 million in 2025 compared to 2024, primarily due to an asset valuation charge for Alliant Energy’s non-utility business in 2025, higher financing 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 2025 compared to 2024 (in millions):

Electric and Gas Revenues and Sales Summary -Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), were as follows:

Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes increased 2% in 2025 compared to 2024, primarily due to changes in temperatures and higher sales to commercial and industrial customers. Alliant Energy’s retail gas sales volumes increased 14% in 2025 compared to 2024, primarily due to changes in temperatures.

Estimated increases (decreases) to operating income from the impacts of temperatures were as follows (in millions):

Electric Sales for Resale - Bulk Power and Other -Bulk power and other volume changes were due to changes in sales in the wholesale energy markets operated by MISO. These changes are impacted by several factors, including the availability and dispatch of Alliant Energy’s EGUs and electricity demand within these wholesale energy markets. Changes in bulk power and other revenues were largely offset by changes in fuel-related costs, and therefore did not have a significant impact on operating income.

Gas Transportation/Other -Gas transportation/other sales volume changes were largely due to changes in the gas volumes supplied to Alliant Energy’s natural gas-fired EGUs caused by the availability and dispatch of such EGUs.

Electric Utility Revenue Variances -The following items contributed to increased (decreased) electric utility revenues for 2025 compared to 2024 (in millions):

(a)In September 2024, the IUC issued an order authorizing an annual base rate increase of $185 million for IPL’s retail electric customers, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, for the October 2024 through September 2025 forward-looking Test Period. Rate changes were effective October 1, 2024, which reflect revenue requirement impacts of increasing electric rate base including investments in solar generation, updated depreciation rates, and certain incremental costs incurred resulting from the 2020 derecho windstorm. In addition, effective October 1, 2024, IPL’s renewable energy rider was discontinued, and certain production tax credits are credited to IPL’s retail electric customers through IPL’s fuel-related cost recovery mechanism. Credits on IPL’s customers’ bills are expected to be offset by a reduction in income tax expense.

(b)In December 2023, the PSCW issued an order authorizing an annual base rate increase of $60 million for WPL’s retail electric customers, covering the 2025 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base including investments in solar generation and energy storage.

(c)Sales for resale bulk power and other revenues increased primarily due to higher prices for electricity and capacity sold by IPL and WPL to MISO wholesale energy markets. These changes were largely offset by changes in electric fuel-related costs.

(d)WPL’s cost recovery mechanism for retail fuel-related expenses supports deferrals of amounts that fall outside an approved fuel monitoring range of forecasted fuel-related expenses determined by the PSCW each year. The difference between revenue collected and actual fuel-related expenses incurred within the fuel monitoring range increases or decreases Alliant Energy’s and WPL’s electric utility revenues. WPL estimates the increase (decrease) to electric utility revenues from amounts within the fuel monitoring range were approximately $4 million and $(4) million in 2025 and 2024, respectively.

Gas Utility Revenue Variances -The following items contributed to increased (decreased) gas utility revenues for 2025 compared to 2024 (in millions):

(a)In September 2024, the IUC issued an order authorizing an annual base rate increase of $10 million for IPL’s retail gas customers, for the October 2024 through September 2025 forward-looking Test Period. Rate changes were effective October 1, 2024, which reflect revenue requirement impacts of increasing gas rate base.

Electric Production Fuel and Purchased Power Expenses Variances -The following items contributed to (increased) decreased electric production fuel and purchased power expenses for 2025 compared to 2024 (in millions):

(a)Electric production fuel costs increased primarily due to higher coal volumes due to higher dispatch of coal-fired EGUs and higher natural gas prices, partially offset by lower natural gas volumes due to lower dispatch of natural gas-fired EGUs.

(b)Purchased power expense increased primarily due to higher prices for electricity purchased by WPL, partially offset by lower volumes of electricity purchased at IPL.

Electric Transmission Service Expense Variances -The following items contributed to (increased) decreased electric transmission service expense for 2025 compared to 2024 (in millions):

Cost of Gas Sold Expense Variances -The following items contributed to (increased) decreased cost of gas sold expense for 2025 compared to 2024 (in millions):

Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2025 compared to 2024 (in millions):

Other Future Considerations -In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations:

•Financing Plans -Alliant Energy currently expects to issue up to $2.4 billion of common stock in aggregate from 2026 through 2029 through the distribution agreement that was executed in May 2025, its Shareholder Direct Plan (up to $25 million in common stock annually) and additional future equity offerings. Refer to Note 7 for discussion of common stock issuances by Alliant Energy in 2025 and Alliant Energy’s at-the-market offering program. In 2026, IPL and WPL currently expect to issue up to $500 million and $300 million, respectively, of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $400 million of long-term debt in aggregate. AEF and Alliant Energy at the parent company level have $500 million ($300 million term loan was retired in January 2026) and $575 million, respectively, of long-term debt maturing in 2026.

•Common Stock Dividends -Alliant Energy announced a 5% increase in its targeted 2026 annual common stock dividend to $2.14 per share, which is equivalent to a quarterly rate of $0.535 per share, beginning with the February 2026 dividend payment. The timing and amount of future dividends is subject to approval of quarterly dividend declarations from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.

•Higher Earnings on Increasing Rate Base -Alliant Energy and WPL currently expect increases in electric utility and gas utility revenues in 2026 compared to 2025 due to impacts from increasing revenue requirements related to investments in the utility business (refer to “Rate Matters” for further discussion). Additionally, Alliant Energy and IPL currently expect electric utility revenues to increase in 2026 compared to 2025 due to the expiration of tax benefit rider credits in 2025. Furthermore, Alliant Energy, IPL and WPL currently expect a decrease in the effective income tax rate in 2026 compared to 2025 due to additional renewable tax credits from renewable generation and energy storage projects placed in service in 2025 and/or expected to be placed in service in 2026. A majority of the differences between actual renewable tax credits and renewable tax credits used to determine rates are recorded in regulatory assets or regulatory liabilities on the balance sheets until they are reflected in future billings to customers. Investment tax credits resulting from IPL energy storage projects placed in service in 2025 and/or expected to be placed in service in 2026 may be utilized to offset any revenue deficiency on an annual basis up to the earnings sharing mechanism threshold included in IPL’s retail electric rate review settlement agreement.

•Sales Trends -Alliant Energy, IPL and WPL currently expect an increase in retail electric sales in 2026 compared to 2025 driven by expected load growth from new customers who currently expect to build data centers in IPL’s and WPL’s service territories. Refer to “Growing Customer Demand” for further discussion.

•Other Operation and Maintenance Expenses - Alliant Energy, IPL and WPL currently expect an increase in other operation and maintenance expenses in 2026 compared to 2025 largely due to higher generation maintenance and energy delivery expenses.

•Depreciation and Amortization Expense - Alliant Energy, IPL and WPL currently expect an increase in depreciation and amortization expense in 2026 compared to 2025 due to capital projects placed in service in 2025 and 2026.

•Interest Expense -Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2026 compared to 2025 due to financings completed in 2025 and planned in 2026 as discussed above.

•Allowance for Funds Used During Construction - Alliant Energy, IPL and WPL currently expect an increase in AFUDC in 2026 compared to 2025 largely due to changes in CWIP balances related to construction activity on capital projects.