ALLIANT ENERGY CORP

Rate Reviews

Retail Base Rate Filings -Base rate changes reflect both returns on additions to infrastructure and recovery of changes in costs incurred or expected to be incurred to provide electric and gas service to retail customers. Given that a portion of the rate changes will offset changes in costs, revenues from rate changes should not be expected to result in an equal change in net income for either IPL or WPL.

IPL’s Retail Electric and Gas Rate Reviews (October 2024 Through September 2025 Forward-looking Test Period) - In September 2024, the IUC issued an order for IPL’s retail electric and gas rate reviews for the October 2024 through September 2025 forward-looking Test Period with rate changes effective October 1, 2024. Key drivers for the rate review included revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation, as well as updated depreciation rates and certain incremental costs incurred resulting from the 2020 derecho windstorm. The IUC’s order included the following provisions:

•Annual retail electric base rate increase of $185 million, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, and a subsequent retail electric base rate moratorium through September 2029;

•During the moratorium, IPL may request updated rates if its actual return on common equity is 100 or more basis points below the authorized return on common equity for a single calendar year or 50 or more basis points below the authorized return on common equity for two consecutive years, and/or if a material change in laws or regulations causes the moratorium to become unsustainable;

•Annual retail gas base rate increase of $10 million;

•Electric earnings sharing mechanism beginning in calendar year 2025, where IPL would apply excess earnings to the remaining net book value of IPL’s highest earning asset with advance ratemaking principles (currently the Emery Generation Station) based on its authorized return on common equity as follows;

•Investment tax credits resulting from renewable generation and energy storage projects may be utilized to offset any revenue deficiency on an annual basis up to IPL’s return on common equity threshold; any remaining investment tax credits, net of the cost of transferability, that are not used to offset any revenue deficiency, will be deferred by IPL and carried forward to offset any revenue deficiency in future years;

•Creation of an individual customer rate tariff, which would allow IPL to attract new load growth to its service territory;

•Electric distribution system investment cap not to exceed $900 million in aggregate or $325 million in any given year from 2026 through 2029, with certain exceptions;

•IPL to retain renewable production tax credits from new generation resources not included in base rates and the repowering of existing wind farms, including the Franklin County wind farm refurbishment, as well as retain energy margins for new generation resources and energy storage;

•Discontinuation of the renewable energy rider; and

•A return of the remaining net book value of the Lansing Generating Station; however, the IUC’s order does not include a return on the remaining net book value of Lansing, resulting in Alliant Energy and IPL recording a pre-tax non-cash charge of $60 million to “Asset valuation charge for IPL’s Lansing Generating Station” in their income statements in 2024.

WPL’s Retail Electric and Gas Rate Reviews (2024/2025 Forward-looking Test Period) - In December 2023, the PSCW issued an order authorizing annual base rate increases of $49 million and $13 million for WPL’s retail electric and gas customers, respectively, effective January 1, 2024, for the 2024 forward-looking Test Period. The PSCW’s order also authorized WPL to implement an additional $60 million increase in annual rates for its retail electric customers, effective January 1, 2025, for the 2025 forward-looking Test Period. The key drivers for the annual base rate increases include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and energy storage. The order extends, with certain modifications, an earnings sharing mechanism through 2025. Under the earnings sharing mechanism, WPL will defer a portion of its earnings if its annual regulatory return on common equity exceeds 9.95% during the 2024/2025 Test Period. WPL must defer 50% of its excess earnings between 9.95% and 10.55%, and 100% of any excess earnings above 10.55%. The PSCW also authorized WPL to defer the incremental under-/over-collection of solar and energy storage renewable tax credits that are different than the approved amounts. Refer to Note 3 for discussion of the PSCW’s 2024 orders related to the deferral of, and deferral of a return on, incremental solar generation construction costs in 2024 and 2025.

WPL’s Retail Fuel-related Rate Filing (2023 Forward-looking Test Period) - In August 2024, the PSCW issued an order authorizing WPL to refund $34 million, plus interest, to its retail electric customers in 2024 for fuel-related costs incurred by WPL in 2023 that were lower than fuel-related costs used to determine rates for such period.

Rate Review Details - Details related to IPL’s and WPL’s key jurisdictions were as follows:

(a)Authorized returns on common equity may not be indicative of actual returns earned or projections of future returns.

(b)Average rate base amounts reflect IPL’s allocated retail share of rate base and do not include CWIP and were calculated using a forecasted 13-month average for the test period.

(c)Average rate base amounts include assets that do not have advance rate-making principles (9.65% return on common equity), production tax credits carryforwards for 1,000 MW of wind generating facilities placed in service in 2019 and 2020 (5% return on common equity), as well as the portion of Whispering Willow - East that does not earn a return on investment.

(d)Average rate base amounts reflect WPL’s allocated retail share of rate base and do not include CWIP or a cash working capital allowance, and were calculated using a forecasted 13-month average for the test period. The PSCW provides a return on selected CWIP and a cash working capital allowance by adjusting the percentage return on rate base.

Planned Rate Review - WPL currently expects to file a retail electric and gas rate review with the PSCW by the end of the second quarter of 2025 for the 2026/2027 forward-looking Test Period. The key drivers for the anticipated filing include revenue requirement impacts of increasing electric and gas rate base. Any rate changes granted from this pending request are expected to be effective on January 1, 2026, with a decision from the PSCW expected by the end of 2025.

LEGISLATIVE MATTERS

In May 2024, the Major Economic Growth Attraction program was enacted in Iowa, which offers various tax incentives for up to two qualified businesses for certain large-scale projects with capital investments greater than $1 billion constructed on certified sites greater than 250 acres in Iowa. The most significant provision of this program for Alliant Energy encourages economic development in IPL’s service territory. Alliant Energy has various development-ready sites throughout Iowa, including the Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, and the Prairie View Industrial Center Super Park in Ames, Iowa.

In May 2024, legislation was enacted in Iowa related to the advance rate-making principles for certain generation and energy storage investments located in Iowa. The most significant provisions of this legislation for Alliant Energy would allow IPL to include energy storage and nuclear-fired generation projects in the advance rate-making principles request process prior to making these investments in Iowa, and require IPL to obtain a certificate of public convenience, use and necessity (GCU Certificate) from the IUC in order to construct energy storage projects.

In July 2023, legislation was enacted in Wisconsin, which creates a sales and use tax exemption for the sale of certain property for qualified data centers. The most significant provision of this legislation for Alliant Energy encourages economic development in WPL’s service territory.

In August 2022, the Inflation Reduction Act of 2022 was enacted. The most significant provisions of the legislation for Alliant Energy, IPL and WPL relate to a 10-year extension of tax credits for clean energy projects, a new production tax credit for eligible solar projects, a new stand-alone investment tax credit for energy storage projects and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers. The new legislation also includes a requirement for corporations with income over $1 billion to pay a 15% minimum tax; however, Alliant Energy is currently below this income level. Alliant Energy, IPL and WPL are utilizing various provisions of the new legislation to enhance the tax benefits expected from their current and planned renewable generation and energy storage projects, including transferring tax credits from such projects to other corporate taxpayers. The impact of these changes is expected to result in more cost benefits for IPL’s and WPL’s customers, higher rate base amounts, additional financing needs expected to be satisfied with additional long-term debt and common stock issuances, and improvements in long-term cash flows over the life of the solar, energy storage and wind projects. Repeal or amendment of the Inflation Reduction Act of 2022, or portions of the Inflation Reduction Act of 2022, could have an adverse impact on Alliant Energy’s, IPL’s and WPL’s financial condition and results of operations. Refer to Note 1(c) for discussion of the transfer of renewable tax credits to other corporate taxpayers in 2023 and 2024.

Refer to Note 11 for discussion of Iowa tax reform enacted in 2022.

LIQUIDITY AND CAPITAL RESOURCES

Overview - Alliant Energy, IPL and WPL expect to maintain adequate liquidity to operate their businesses and implement their strategy as a result of operating cash flows generated by their utility business, and available capacity under a single revolving credit facility and IPL’s sales of accounts receivable program, supplemented by periodic issuances of long-term debt and Alliant Energy equity securities. As summarized below, Alliant Energy, IPL and WPL believe they have the ability to generate and obtain adequate amounts of cash to meet their requirements and plans for cash in the next 12 months and beyond.

Liquidity Position -At December 31, 2024, Alliant Energy had $81 million of cash and cash equivalents, $742 million ($275 million at the parent company, $250 million at IPL and $217 million at WPL) of available capacity under the single revolving credit facility and $40 million of available capacity at IPL under its sales of accounts receivable program.

Capital Structure -Alliant Energy, IPL and WPL plan to maintain debt-to-total capitalization ratios that are consistent with investment-grade credit ratings, as well as maintain capital structures consistent with the authorized levels approved by IPL’s and WPL’s regulators. Financial capital structures as of December 31, 2024 were as follows (Common Equity (CE); Long-term Debt (including current maturities) (LD); Short-term Debt (SD)):

Alliant Energy, IPL and WPL intend to manage their capital structures and liquidity positions in such a way that facilitates their ability to raise funds reliably and on reasonable terms and conditions, while maintaining capital structures consistent with those approved by regulators. In addition to capital structures, other important factors used to determine the characteristics of future financings include financial coverage ratios, capital spending plans, regulatory orders and rate-making considerations, levels of debt and equity imputed by rating agencies, market conditions, the impact of tax initiatives and legislation, and any potential proceeds from asset sales. The PSCW factors certain imputed debt adjustments, including certain lease obligations, in establishing a regulatory capital structure as part of WPL’s retail rate reviews. The IUC does not make any explicit adjustments for imputed debt in establishing capital ratios used in determining customer rates, although such adjustments are considered by IPL in recommending an appropriate capital structure. Debt imputations by rating agencies include, among others, pension and OPEB obligations, the sales of accounts receivable program and certain lease obligations.

Credit and Capital Markets -Alliant Energy, IPL and WPL maintain a single revolving credit facility to provide backstop liquidity to their commercial paper programs, and ensure a committed source of liquidity in the event the commercial paper market becomes disrupted. In addition, IPL maintains a sales of accounts receivable program as an alternative financing source; however, if customer arrears were to exceed certain levels, IPL’s access to the program may be restricted.

Primary Sources and Uses of Cash - Alliant Energy’s most significant source of cash is from electric and gas sales to IPL’s and WPL’s customers. Cash from these sales reimburses IPL and WPL for prudently-incurred expenses to provide service to their utility customers and generally provides IPL and WPL a return of and a return on the assets used to provide such services. Capital needed to retire debt and fund capital expenditures related to large strategic projects is expected to be met primarily through external financings.

Cash Flows - Selected information from the cash flows statements was as follows (in millions):

Operating Activities -The following items contributed to increased (decreased) operating activity cash flows for 2024 compared to 2023 (in millions):

(a)Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers in 2023 and 2024.

Income Tax Payments and Receipts - Income tax (payments) receipts were as follows (in millions):

Alliant Energy, IPL and WPL currently do not expect to make any significant federal income tax payments over the next few years based on their current credit carryforward positions; however, some tax payments and receipts may occur for state taxes and between consolidated group members (including IPL and WPL) under the tax sharing agreement between Alliant Energy and its subsidiaries. Refer to Note 11 for discussion of the carryforward positions.

As discussed in “Legislative Matters,” the Inflation Reduction Act of 2022 provides the right to transfer renewable tax credits to other corporate taxpayers. Refer to the cash flows statements and Note 1(c) for details of renewable tax credits transferred to other corporate taxpayers in 2023 and 2024. Alliant Energy, IPL and WPL currently intend to transfer all eligible renewable tax credits in the future, and as a result, expect an increase in future cash flows from operating activities.

Higher Earnings on Increasing Rate Base - Refer to “Other Future Considerations” for discussion of expected increases in future cash flows from operating activities resulting from higher earnings on increasing rate base at IPL and WPL.

Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $20 million, $1 million and $14 million of pension plan contributions in 2025, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2024 measurement date. Refer to Note 12(a) for discussion of pension plan contributions in 2024 and the current funded levels of pension plans.

Investing Activities -The following items contributed to increased (decreased) investing activity cash flows for 2024 compared to 2023 (in millions):

(a)Largely due to higher expenditures for IPL’s and WPL’s energy storage, IPL’s solar generation and IPL’s refurbishment of an existing wind farm, partially offset by lower expenditures for WPL’s solar generation.