Below is a summary of updates to significant regulatory proceedings and related legal proceedings. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of the Form 10-K for additional information and a summary of our regulatory frameworks. We are unable to predict the ultimate outcome of these matters, the timing of final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.

In June 2024, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service by $446 million. The electric rate increase request is based on a 10.25% return on common equity, a capital structure composed of 52% common equity, a rate base of $14 billion, and a test year ended March 31, 2024, with certain pro-forma adjustments expected through an anticipated true-up date of December 31, 2024. Ameren Missouri also requested the continued use of the FAC and trackers for pension and postretirement benefits, uncertain income tax positions, certain excess deferred income taxes, and the utilization of production and investment tax credits or proceeds from the sale of tax credits allowed under the IRA, which the MoPSC previously authorized in earlier electric rate orders. The electric rate increase request reflects the following:

•increased infrastructure investments made under Ameren Missouri’s Smart Energy Plan, including increased cost of capital and depreciation expense. Included in these investments are 500 megawatts of solar generation investment for the Boomtown, Cass County and Huck Finn solar projects along with investments in the Callaway nuclear energy center and other dispatchable generation to support a reliable, low-cost and cleaner mix of energy resources;

The MoPSC proceeding relating to the proposed electric service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by May 2025 and new rates effective by June 2025. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, whether the requested regulatory recovery mechanisms will be continued, or whether any rate change that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the rate change goes into effect.

Agreement type

Facility size

Status of MoPSC CCN

Status of FERC approval of acquisition

Anticipated in-service date(a)

Huck Finn Solar Project(b)(c)

Build-transfer

200-MW

Approved February 2023

Received March 2023

Fourth quarter 2024

Boomtown Solar Project(c)(d)

Build-transfer

150-MW

Approved April 2023

Received October 2023

Fourth quarter 2024(e)

Cass County Solar Project(d)

Development-transfer(f)

150-MW

Approved June 2024

Not applicable

Fourth quarter 2024

Vandalia Solar Project(c)(g)

Self-build

50-MW

Approved March 2024

Not applicable

Fourth quarter 2025

Bowling Green Solar Project(c)(g)

Self-build

50-MW

Approved March 2024

Not applicable

First quarter 2026

Split Rail Solar Project(g)

Build-transfer

300-MW

Approved March 2024

Requested July 2024

Mid-2026

Castle Bluff Natural Gas Project

Self-build

800-MW

Filed June 2024

Not applicable

Fourth quarter 2027

In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by a wholly owned, special purpose subsidiary of Ameren Missouri to finance approximately $470 million of costs related to the planned accelerated retirement of the Rush Island Energy Center, which includes the expected remaining unrecovered net plant balance associated with the facility, among other costs. Ameren Missouri initially petitioned the MoPSC in November 2023 to finance $519 million of costs. The difference between the initial petition and final financing order will be considered for recovery in future rate proceedings involving the securitized utility tariff charge or base rates. Ameren Missouri will collect the amounts necessary to repay the bonds over approximately 15 years from the date of bond issuance. The financing order also includes a determination that the decision to retire the Rush Island Energy Center was reasonable and prudent. The MoPSC did not make a determination regarding the prudency of Ameren Missouri's prior actions that resulted in the adverse ruling in the NSR and Clean Air Act litigation discussed in Note 9 – Commitments and Contingencies. However, claims regarding such actions could be considered in future regulatory proceedings. If future regulatory proceedings result in revenue reductions based on Ameren Missouri’s prior actions that resulted in the adverse ruling in the NSR and Clean Air Act litigation, it could have a material adverse effect on the results of operations, financial position, and liquidity of Ameren and Ameren Missouri. In July 2024, the MoOPC filed a request for rehearing of the financing order. Ameren Missouri expects a decision on the rehearing request in August 2024. The decision on the rehearing request is subject to appeal. The timing of the issuance of securitized utility tariff bonds is dependent on the conclusion of any appeal process.

In January 2024, Ameren Missouri filed a proposed customer energy-efficiency plan with the MoPSC under the MEEIA. This filing proposed a three-year plan, which includes a portfolio of customer energy-efficiency programs, along with the continued use of the MEEIA rider, which allows Ameren Missouri to collect from customers its actual MEEIA program costs and related lost electric revenues. If the plan is approved, Ameren Missouri intends to invest $123 million annually in the proposed customer energy-efficiency programs from 2025 to 2027. In addition, Ameren Missouri requested performance incentives applicable to each plan year to earn revenues by achieving certain customer energy-efficiency savings and target spending goals. If 100% of the goals are achieved, Ameren Missouri would earn performance incentive revenues totaling $56 million over the three-year plan. Ameren Missouri also requested additional performance incentives applicable to each plan year totaling up to $14 million over the three-year plan, if Ameren Missouri exceeds 100% of the goals. In March 2024, the MoPSC staff and the MoOPC filed responses in opposition to the proposed customer energy-efficiency plan under the MEEIA. Ameren Missouri expects a decision by the MoPSC by October 2024, but cannot predict the ultimate outcome of this regulatory proceeding.

In July 2022, the MISO approved the first tranche of projects related to a preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned or awarded via a competitive bid process to various utilities, including Ameren. In July 2024, ATXI filed a request for a CCN, among other things, with the MoPSC related to a portion of the MISO long-range transmission projects that it will construct within the MoPSC’s jurisdiction. A decision by the MoPSC is expected by mid-2025.

In December 2023, the ICC issued an order in Ameren Illinois' MYRP proceeding approving base rates for electric distribution services for 2024 through 2027 and rejecting Ameren Illinois' Grid Plan, which was addressed as part of the MYRP proceeding. Rate changes consistent with the December 2023 order became effective in January 2024 and remained effective through late June 2024, when new rates became effective pursuant to the June 2024 ICC rehearing order discussed below. The December 2023 order adopted an alternative methodology to establish a rate base and revenue requirements for the years 2024 through 2027 using Ameren Illinois’ previously approved 2022 year-end rate base. In January 2024, the ICC partially denied a rehearing requested by Ameren Illinois to revise the allowed ROE in the December 2023 order and granted Ameren Illinois’ rehearing request to reconsider the rate base for each year of the MYRP and to include a base level of investments to maintain grid reliability in each year of the MYRP. In June 2024, the ICC issued an order on Ameren Illinois’ rehearing request, which revised the rate bases for Ameren Illinois’ MYRP test years to include investments for 2023 through 2027, among other things. New rates became effective in late June 2024. For additional information on the ICC’s June 2024 rehearing order, see the table below. In July 2024, Ameren Illinois filed a request for rehearing of the ICC’s June 2024 rehearing order to include an asset associated with other postretirement benefits in the rate base. Subsequently, in August 2024, the ICC denied the rehearing request. The ICC rehearing denial

In July 2024, Ameren Illinois filed an update to its revised Grid Plan and revised MYRP to update the requested revenue requirements for 2024 through 2027. In July 2024, the ICC staff filed its recommendation regarding Ameren Illinois’ revised MYRP. An ICC decision on the revised Grid Plan and updated revenue requirements is expected by the end of 2024 with rates effective in January 2025.


Year	Revenue Requirement (in millions)	Average Annual Rate Base (in billions)
ICC’s June 2024 Rehearing Order(a):
2024	$1,196	$4.0
2025	$1,282	$4.3
2026	$1,350	$4.5
2027	$1,397	$4.7
Ameren Illinois’ July 2024 Revised MYRP(a):
2024	$1,215	$4.3
2025	$1,300	$4.5
2026	$1,386	$4.8
2027	$1,446	$5.0
ICC Staff’s July 2024 Revised MYRP(a):
2024	$1,201	$4.2
2025	$1,281	$4.4
2026	$1,361	$4.6
2027	$1,414	$4.8

In April 2024, Ameren Illinois filed for a reconciliation adjustment to its 2023 electric distribution service revenue requirement with the ICC. In July 2024, Ameren Illinois filed a revised reconciliation adjustment, requesting recovery of $158 million. The reconciliation adjustment reflects a capital structure composed of 50% common equity and Ameren Illinois’ actual 2023 recoverable costs and year-end rate base. In June 2024, the ICC staff submitted its calculation of the reconciliation adjustment, recommending recovery of $157 million. An ICC decision in this proceeding is required by December 2024, and any approved adjustment would be collected from customers in 2025. This is the final revenue requirement reconciliation under the IEIMA formula framework.

In November 2023, the ICC issued an order in Ameren Illinois’ January 2023 natural gas delivery service regulatory rate review, which resulted in an increase to its annual revenues for natural gas delivery service of $112 million based on a 9.44% allowed ROE, a capital structure composed of 50% common equity, and a rate base of approximately $2.85 billion. The order reflected a reduction of approximately $93 million of planned distribution and transmission capital investments included in Ameren Illinois’ requested revenue increase, which used a 2024 future test year. The new rates became effective on November 28, 2023.

In December 2023, Ameren Illinois filed a request for rehearing of the ICC’s November 2023 order. The filing requested the ICC revise the order to include an allowed ROE of at least 9.89%, a capital structure composed of 52% common equity, and the reversal of the approximately $93 million reduction of planned distribution and transmission capital investments included in the order, among other things. In January 2024, the ICC denied Ameren Illinois’ rehearing request. Subsequently, in January 2024, Ameren Illinois filed an appeal of the November 2023 ICC order to the Illinois Appellate Court for the Fifth Judicial District. The court is under no deadline to address the appeal. Ameren Illinois cannot predict the ultimate outcome of this appeal.

In March 2021, Ameren Illinois filed a request with the ICC to initiate a reconciliation proceeding to determine the accuracy and prudence of natural gas capital investments recovered under the QIP rider during 2020. In October 2023, the Illinois Attorney General’s office challenged the recovery of capital investments that were made during 2020, alleging that the ICC should disallow approximately $53 million in natural gas capital investments as improper and imprudent, providing a potential over-recovery of approximately $3 million in 2020. In October 2023, the ICC staff filed testimony that supports the prudence and reasonableness of the capital investments made during 2020. Ameren Illinois’ 2020 QIP rate recovery request under review by the ICC was within the rate increase limitations allowed by law. The ICC is under no deadline to issue an order in this proceeding. Ameren Illinois cannot predict the ultimate outcome of this regulatory proceeding.

In July 2022, the MISO approved the first tranche of projects related to a preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned or awarded via a competitive bidding process to various utilities, including Ameren. In February 2024, Ameren Illinois and ATXI filed a request for a CCN, among other things, with the ICC related to the portion of the MISO long-range transmission projects they will construct within the ICC’s jurisdiction. A decision by the ICC is expected by mid-2025.

Since November 2013, the allowed base ROE for FERC-regulated transmission rate base under the MISO tariff has been subject to customer complaint cases and has been changed by various FERC orders. In May 2020, the FERC issued an order, which set the allowed base ROE to 10.02% and required refunds, with interest, for the periods November 2013 to February 2015 and from late September 2016 forward. Ameren and Ameren Illinois paid these refunds, including interest, by March 31, 2022. In June and July 2020, Ameren Missouri, Ameren Illinois, and ATXI, as well as various customers, petitioned the United States Court of Appeals for the District of Columbia Circuit for review of the May 2020 order, challenging certain aspects of the new ROE methodology established. The petition filed by Ameren Missouri, Ameren Illinois, and ATXI challenged the refunds required for the period from September 2016 to May 2020. In August 2022, the court issued a ruling that granted the customers’ petition for review, vacated the FERC’s previous MISO ROE-determining orders, and remanded the proceedings to the FERC. The court elected not to rule on the issues raised by Ameren Missouri, Ameren Illinois, and ATXI. The currently allowed base ROE of 10.02% will remain effective for customer billings, but the transmission rates charged during previous periods and the currently effective rates may be subject to refund if the base ROE is changed by the FERC in a future order. The FERC is under no deadline to issue an order related to these proceedings. A 50-basis-point change in the FERC-allowed ROE would affect Ameren’s and Ameren Illinois’ annual revenue by an estimated $21 million and $15 million, respectively, based on each company’s 2024 projected rate base. Ameren and Ameren Illinois are unable to predict the ultimate resolution of this matter; however, such resolution could have a material effect on their results of operations, financial position, and liquidity.