Ameren Illinois customers will pay a supply price of 11.326 cents per kilowatt-hour from June 1 through September 30, the utility’s summer rate that goes into effect as the cooling season begins.
That price is roughly 39% higher than Ameren’s summer supply rate two years ago, a jump that matters because supply charges are the portion of bills tied to wholesale market conditions rather than delivery. The increase lands at a time when customers typically see larger energy use and higher bills.
Market pressure is the immediate driver. Rising electricity demand — including load growth tied to new and proposed data centers — has nudged wholesale costs up across suppliers, tightening the pool of low-cost supply available to retail providers and utilities alike.
The Citizens Utility Board says Ameren remains the better option for many customers given the current market, a conclusion that reflects both the new Ameren supply price and the pitfalls of alternative offers. Alternative electricity suppliers are operating under the same market strain that pushed Ameren’s rate higher, and many retail offers come with introductory “teaser” prices, extra monthly fees, or contract provisions that raise costs after a short period.
That mismatch is the tension for consumers deciding whether to switch. CUB warns that switching can cost more than staying with the utility because advertised low rates often expire, hidden fees can appear, and automatic contract renewals can trap customers at higher prices. The group also highlights a broader loss: Illinois consumers have lost about $2 billion to alternative suppliers since 2015, by CUB’s estimate.
Consumers should remember that alternative suppliers affect only the supply portion of an electric bill and will not shield them from future utility delivery-rate increases. CUB’s practical advice for households trying to limit summer bills includes pursuing energy-efficiency measures, enrolling in payment-assistance programs where eligible, and running careful comparisons of any supplier offer — looking past headline rates to the full contract terms and fees.
The board also cautions against sharing account details with door-to-door sales representatives; giving a bill or account number can enable unauthorized switches, a practice known as slamming. Those protections matter because the immediate rate is only part of a multi-piece monthly bill and unexpected contract language can erase short-term savings.
Looking ahead, Ameren’s next supply rate covering October 2026 through May 2027 is expected to decrease, but that rate has not been finalized. What the record does not yet answer is how much an individual household’s monthly bill will change this summer — the exact impact depends on each customer’s consumption, rate class and any contract terms with a retail supplier.
For now, the plain outcome is that supply costs will be higher for Ameren Illinois customers over the June–September window, and switching suppliers is not a guaranteed path to lower bills. Customers should prepare for larger summer supply charges, compare any offers closely, use efficiency and assistance options where available, and watch for contract terms that could reverse short-term savings.
