Slides
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July 1, 2025 Iowa Advance Ratemaking Filing Alliant Energy Corporation
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2 Cautionary Statements Forward-looking Statements The information on slide 4 contains forward-looking statements. Actual results could differ materially because the realization of those results is subject to many uncertainties, including: regulatory action on IPL’s advanced ratemaking filing; regulatory or governmental actions; economic and political conditions in IPL’s service territory; the ability to obtain regulatory approval for investments and upgrades with acceptable conditions; and other factors discussed in more detail in Alliant Energy Corporation’s SEC filings. Alliant Energy cannot provide any assurance that the assumptions used in the forward-looking statements or otherwise are accurate or will prove to be correct. All forward- looking statements included in this presentation are based upon information presently available, and Alliant Energy assumes no obligation to update any forward-looking statements.
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3 Advance Ratemaking in Iowa ✓ Utilities in Iowa can petition the Iowa Utilities Commission (IUC) to establish rate-making principles before they build or acquire new generation facilities or make significant alterations to existing ones. ✓ This process allows utilities to gain certainty on recovery of costs proactively and helps reduce their financial risk related to these future investments. ✓ During Advance Ratemaking, the IUC reviews testimony and exhibits to evaluate aspects such as the availability of alternative electricity sources and the project's reasonableness in comparison to those alternatives. Utilities must show they considered other sources and that their plan is reasonable and in the best interest for customers compared to viable alternatives.
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4 Iowa Advance Ratemaking filing – Docket RPU-2025-0003 Summary of Request for up to 1,000 megawatts of Wind Regulatory approval Filed advance ratemaking principles July 1, 2025 Decision expected Q1 2026 Anticipated level of tax credits 100% Requested return on equity 11.25% Expected depreciable life 40 years