PUBLIC NOTICE Notice of Proposed Tariff Changes Gas Service Schedule Ill. C. C. No. 2 To the Gas Patrons of Ameren Illinois Company d/b/a Ameren Illinois: Ameren Illinois (or Company) hereby gives notice to the public that on April 23, 2026, it filed with the Illinois Commerce Commission (ICC or Commission) evidence (direct testimony) regarding the reconciliation of revenues and costs under the Company's Purchased Gas Adjustment (PGA) Rider with costs incurred in connection with the cost of gas from January 1, 2025 through December 31, 2025. The evidence is applicable to Rate Zone I (formerly the AmerenCIPS service territory), Rate Zone II (formerly the AmerenCILCO service territory) and Rate Zone III (formerly the AmerenIP service territory); and may result in changes in its rates and charges with respect to gas delivery services throughout the Company's gas service territory in Illinois. The changes in rates and charges will take effect after hearings and after the Commission issues its final Order. The Commission docketed the filing as Docket No. 25-1013. A copy of the evidence may be inspected at Ameren Illinois' offices located at 300 Liberty Street, Peoria, Illinois or online at www.icc.illinois.gov/e-docket/. All parties interested in this matter may obtain information with respect thereto either directly from Ameren Illinois or by addressing the Chief Clerk of the Illinois Commerce Commission, 527 East Capitol Avenue, Springfield, Illinois 62706. AMEREN ILLINOIS COMPANY d/b/a Ameren Illinois By: Patrick E. Smith, President IPL0335596 May 6,13 2026