Regulatory Matters (Details) - USD ($)
$ in Millions

6 Months Ended

Nov. 29, 2024

Jun. 30, 2025

Dec. 31, 2024

Regulatory assets, non-current

$ 131.4

$ 140.0

Schedule of Regulatory Assets and Liabilities [Text Block]

REGULATORY MATTERS

Ohio Legislation, AES Ohio ESPs and Smart Grid Plans

Ohio Energy Legislation

On April 30, 2025, the Ohio legislature passed new energy legislation (Sub. HB 15) that was signed by the Governor and will be effective August 14, 2025. The legislation allows Ohio’s electric utilities to file three-year forecasted base distribution rate cases, which would replace electric security plans (ESPs) and associated recovery riders. Among other provisions, the legislation eliminates as of its effective date, the LGR, which currently allows for recovery of net OVEC costs and revenues. Changes to the regulatory framework from this legislation, including the recovery of any remaining regulatory asset balance amounts or future net OVEC costs and revenues, could be material to our results of operations, financial condition and cash flows. As of June 30, 2025, AES Ohio established a reserve of $3.2 million for the LGR regulatory asset.

AES Ohio ESP

Current Ohio law requires utilities to file either an ESP or MRO plan to establish SSO rates. AES Ohio is currently operating pursuant to ESP 4, described in the paragraph below. From November 1, 2017 through December 18, 2019, AES Ohio operated pursuant to an approved ESP plan, which was initially approved on October 20, 2017 (ESP 3). On December 18, 2019, the PUCO approved AES Ohio's Notice of Withdrawal of ESP 3 and reversion to its prior rate plan (ESP 1). Among other items, the PUCO Order approving the ESP 1 rate plan included reinstating the non-bypassable RSC Rider, which provided annual revenue of approximately $79.0 million. The OCC has appealed to the Ohio Supreme Court the PUCO’s decision approving the reversion to ESP 1 as well as argued for a

refund of the RSC revenue dating back to August 2021. Oral arguments regarding this appeal were held on April 22, 2025, and a court decision is pending.

Smart Grid Comprehensive Settlement

On October 23, 2020, AES Ohio entered into a Stipulation and Recommendation (the Settlement) with the staff of the PUCO, various customers and organizations representing customers of AES Ohio and certain other parties with respect to, among other matters, AES Ohio's applications for (i) approval of AES Ohio's plan to modernize its distribution grid (Smart Grid Phase 1), (ii) findings that DP&L passed the SEET for 2018 and 2019, and (iii) findings that AES Ohio's ESP 1 satisfies the SEET and the more favorable in the aggregate (MFA) regulatory test. On June 16, 2021, the PUCO issued their opinion and order accepting the stipulation as filed. The OCC appealed the final PUCO order with respect to the 2018 and 2019 SEET to the Ohio Supreme Court on December 6, 2021. Oral arguments regarding this appeal were held on April 2, 2025, and a court decision is pending.

Smart Grid Phase 2 Plan

In February 2024, AES Ohio filed a Smart Grid Phase 2 with the PUCO proposing a ten-year investment plan to begin after Smart Grid Phase 1 ends. On September 13, 2024, AES Ohio reached a settlement with the PUCO staff and other parties on the pending Smart Grid Phase 2 application and an evidentiary hearing was held on October 29, 2024. A fundamental premise of the Application was the continued availability of rider recovery of Smart Grid investments through the plan period. However, with the recent enactment of Sub. HB 15 described above, which prohibits AES Ohio from applying for a new electric security plan which includes certain rider recovery mechanisms, as well as the near-term financial uncertainty created by the statute, AES Ohio withdrew its Smart Grid Phase 2 Application on May 23, 2025. On July 9, 2025, the PUCO approved the withdrawal and closed the case. This withdrawal will provide AES Ohio flexibility as to the timing and scope of Smart Grid investments to continue to deliver benefits to customers.

Distribution Rate Case

2024 Distribution Rate Case application

On November 29, 2024, AES Ohio filed a distribution rate case with the PUCO. The investments reflected in this distribution rate case include investments to enhance the safety, reliability, and resilience of the distribution system. Among other matters, the application requests:

•An increase to its annual distribution revenue requirement of $235.2 million, which incorporates certain investments that are currently recovered through the Distribution Investment Rider;

•A return on equity of 10.95% and a cost of long-term debt of 4.49% on a distribution rate base of $1.3 billion and based on a capital structure of 53.87% equity and 46.13% long-term debt; and

•A date certain of September 30, 2024 and a test period of June 1, 2024 – May 31, 2025

The rate case application also includes a proposal for increased tree-trimming expenses. On June 27, 2025, the PUCO Staff submitted their Report and Recommendations; the PUCO has set the evidentiary hearing to begin September 9, 2025 and public hearings to be held on August 7 and August 14, 2025.

Tax Savings Credit Rider

Public Utilities, General Disclosures [Line Items]

Reserve for Regulatory Asset

$ 3.2

Tax Savings Credit Rider

13.6

Subsidiaries [Member]

Cost of Long-term Debt - Distribution Rate Case

4.49%

Revenue Increase - Distribution Rate Case

$ 235.2

Return on Equity - Distribution Rate Case