The chart above is Ameren Illinois' residential Price to Compare for every month the Illinois Commerce Commission has posted since January 2017. On June 1, 2026 it went from 8.769 to 11.326 cents per kWh, a step of about 29 percent. ComEd's posted price moved the same day from 9.660 to 10.399, about 7.7 percent. This page goes through what that number is, how the step compares with the record behind it, what moved in the same seasons at the grid operator Ameren Illinois belongs to, and what the step can and cannot do to a bill.
Every rate here is a figure the ICC posted. Nothing is a forecast. No Ameren Illinois bill has been reconciled by Phantom Grid, so none of this is reconciled to a bill, and no Ameren delivery rate appears anywhere on the page.
What is the Ameren Illinois Price to Compare?
The Price to Compare is the price Ameren Illinois charges for the electricity itself to a residential customer who has not chosen a retail supplier. It is the supply half of the bill only. Delivery, the charge for the wires, is billed separately and is not in this number.
The ICC publishes it on its Plug In Illinois site and keeps the full history in a workbook, Historical Prices to Compare, with a ComEd section and an Ameren Illinois section. The Ameren section prints three figures a month for residential non-space heat customers: the Price to Compare, a separate price for usage above 800 kWh in the months it applies, and the Purchased Electricity Adjustment. The current posting, on the Plug In Illinois Ameren Illinois page, is 11.326 cents per kWh for June 1 through September 30, 2026.
Did Ameren Illinois raise its rates in 2026?
The posted supply price rose on June 1, 2026, from 8.769 to 11.326 cents per kWh. That is the answer to the question most people are asking, and it is true.
It is also the start of Ameren's summer window, and the posted price has moved at the start of June in every year on record. Compared with the same summer window a year earlier the June 2026 price is lower, not higher: 11.326 against 12.180 in June 2025, down 0.854 cents, about 7 percent. The months before the step went the other way. January through May 2026 was posted at 8.769, against 8.277 for January through May 2025, up 0.492 cents, about 6 percent.
So "did Ameren raise rates in 2026" has two honest answers depending on what the question compares. Against May, yes, by 29 percent. Against last summer, the posted price is lower.
How much did Ameren raise its rates?
Here are the posted figures around the step, beside ComEd's for the same months, straight from the ICC workbook.
| posted month | Ameren Illinois, cents per kWh | Ameren, usage above 800 kWh | ComEd, cents per kWh |
|---|---|---|---|
| June 2025 | 12.180 | not printed | 10.028 |
| October 2025 | 8.402 | 7.483 | 9.689 |
| January 2026 | 8.769 | 7.850 | 9.660 |
| May 2026 | 8.769 | 7.850 | 9.660 |
| June 2026 | 11.326 | not printed | 10.399 |
| September 2026 | 11.326 | not printed | 10.399 |
From May to June 2026 Ameren's posted price rose 2.557 cents per kWh, about 29 percent. ComEd's rose 0.739 cents, about 7.7 percent. Year over year, June to June, Ameren's fell 0.854 cents while ComEd's rose 0.371, about 3.7 percent.
As an illustration only, the posted price times a stated 800 kWh: at 8.769 cents that is $70.15, and at 11.326 cents it is $90.61, a difference of $20.46 on the supply price alone. That is arithmetic on two posted figures and a kWh number chosen for the example, not anyone's bill.
The June step has happened before, and it has gone both ways
Ameren's posted price changes at the start of January, June and October, and only once in the record, July 2022, did it move in between, by 0.005 cents. From October through May the workbook also prints the lower price for usage above 800 kWh; from June through September it prints one price. Here is every May to June change in the record.
| year | May, cents per kWh | June, cents per kWh | change |
|---|---|---|---|
| 2017 | 6.519 | 5.369 | down 17.6 percent |
| 2018 | 6.162 | 4.658 | down 24.4 percent |
| 2019 | 5.026 | 4.561 | down 9.3 percent |
| 2020 | 4.707 | 4.396 | down 6.6 percent |
| 2021 | 4.553 | 4.821 | up 5.9 percent |
| 2022 | 5.478 | 10.623 | up 93.9 percent |
| 2023 | 11.833 | 7.877 | down 33.4 percent |
| 2024 | 8.683 | 8.136 | down 6.3 percent |
| 2025 | 8.277 | 12.180 | up 47.2 percent |
| 2026 | 8.769 | 11.326 | up 29.2 percent |
In six of the ten years the June price went down. Of the four years it went up, three went up by more than a quarter, 2022, 2025 and 2026, and 2026 is the smallest of those three. The low of the whole record is 4.396 cents in June 2020 and the high is 12.236 cents in October 2022.
What the capacity auction did in the same seasons
Ameren Illinois is in MISO, the regional grid operator for its territory. Each spring MISO runs its Planning Resource Auction, which prices generating capacity for the planning year that starts June 1, separately for summer, fall, winter and spring. Here are MISO's published summer prices for its North/Central zones, Zones 1 to 7, which MISO's 2026 release says include portions of Illinois, beside Ameren's posted price for the same June:
| summer of | MISO summer clearing price, dollars per MW-day | Ameren posted price in June, cents per kWh |
|---|---|---|
| 2023 | 10.00 | 7.877 |
| 2024 | 30.00 | 8.136 |
| 2025 | 666.50 | 12.180 |
| 2026 | 424.30 | 11.326 |
The 2023 to 2025 prices are from MISO's results posting for Planning Year 2025-26, which lists the historical summer prices; the 2026 price is from MISO's release of April 28, 2026. The two sets of numbers rank the same way: the two cheap capacity summers were the two Junes the posted price fell, the most expensive capacity summer was the highest June price, and 2026 sits below 2025 on both.
The June 2026 step itself lands on a season boundary in the same results. The spring season that ended May 31, 2026 cleared at $69.88 per MW-day in those zones, and the summer that began June 1 cleared at $424.30.
What this does not show is how much of the 11.326 cents is capacity. The ICC posting does not break the Price to Compare into energy and capacity, and MISO's results do not price anyone's supply rate, so this page does not put a number on that share. The seasons line up; the split is not on file here.
The adjustment beside the price, month by month
The Purchased Electricity Adjustment is a separate figure the ICC lists next to the Price to Compare every month. It is not part of the Price to Compare. On Ameren's record it is usually a small credit, below zero in 94 of the 117 months posted, and once it was not small. Here is the last thirteen months exactly as the sheet prints it; the chart above draws every month since 2017.
| posted month | Purchased Electricity Adjustment, cents per kWh |
|---|---|
| September 2025 | -0.142 |
| October 2025 | 0.303 |
| November 2025 | 0.276 |
| December 2025 | -4.996 |
| January 2026 | -0.456 |
| February 2026 | -0.519 |
| March 2026 | -0.579 |
| April 2026 | -0.880 |
| May 2026 | 0.139 |
| June 2026 | -0.055 |
| July 2026 | -0.095 |
| August 2026 | -0.144 |
| September 2026 | -0.200 |
December 2025 is the outlier: a credit of 4.996 cents per kWh, the deepest in the record. As an illustration only, on a stated 800 kWh that is a $39.97 credit. A bill that carried a credit like that makes the next bill look much larger by comparison, with no change in the price.
Why did my Ameren bill double?
Not because of the posted supply price by itself. The June 2026 step was about 29 percent, and a price that rises 29 percent cannot double a bill on its own. It raises the supply half, and the delivery half is billed separately.
A bill that doubled had something else move with it, and every one of these is printed on the bill itself:
The kilowatt hours. Usage is the first number to check. A summer bill that covers air conditioning months can carry far more kWh than a spring bill, and more kWh at a higher price compounds. Compare the kWh on this bill with the same month a year earlier, not with last month.
The number of days. A billing period of thirty five days is not comparable to one of twenty eight. The service dates are printed on the bill.
An estimated read. An estimated read followed by an actual read lands the correction in one bill. Check whether the bill marks the read as estimated before comparing it with anything.
A credit on the bill before. If the previous bill carried a large credit, such as the adjustment in December 2025, the bill after it looks larger with no change in the price.
The price for usage above 800 kWh. From October through May the posting prints a lower price above 800 kWh, 7.850 cents from January through May 2026. From June through September it prints no separate price above 800 kWh. If your home uses more than 800 kWh a month, read the price per kWh on each supply line of your own bill rather than the headline figure.
To find which one it was on your bill, your Ameren Illinois bill is high: which part of it actually moved walks the four causes in order, using only bills you already have.
Check your own bill against the posting
The chart above is the record. Put the supply price printed on your Ameren Illinois bill next to the posting for the months your bill covers, and the kWh next to the same month a year earlier. That separates the price from the usage, which is the split this whole question turns on.
The bill check below reads your own Ameren Illinois bill line by line. Nothing on this page prices an Ameren Illinois bill, and none of the figures above is reconciled to one.
Did Ameren Illinois raise its rates in 2026?
Ameren Illinois' posted residential Price to Compare rose from 8.769 to 11.326 cents per kWh on June 1, 2026, about 29 percent. Compared with June 2025, when it was posted at 12.180, the June 2026 price is about 7 percent lower. January through May 2026 was posted at 8.769, about 6 percent above the same months of 2025.
How much did Ameren raise its rates?
The posted supply price rose 2.557 cents per kWh from May to June 2026. As an illustration only, on 800 kWh that is $20.46 more on the supply price. ComEd's posted price rose 0.739 cents the same month.
Why is Ameren Illinois raising rates?
The ICC posting does not state a cause. What is on file is that MISO's capacity auction, which covers Ameren Illinois' region, cleared the spring that ended May 31, 2026 at $69.88 per MW-day and the summer that began June 1 at $424.30, and Ameren's posted price stepped up on that date. MISO's summer prices and Ameren's June prices have ranked the same way in each of the last four summers. How much of the posted price is capacity is not stated by either source.
Why did my Ameren bill double?
A 29 percent rise in the posted supply price does not double a bill on its own. Check the kWh against the same month last year, the number of days in the billing period, whether the read was estimated, and whether the previous bill carried a credit.
Will Ameren Illinois increase rates again?
This page does not forecast. The current posted window runs June 1 through September 30, 2026. The chart above adds each month as the ICC posts it.
Does this include Ameren's delivery charges?
No. The Price to Compare is the supply half of the bill. This page quotes no Ameren delivery rate.
References