CHICAGO — A law originally enacted to keep the state’s nuclear fleet profitable is instead giving relief to energy customers due to rising power costs and increased federal subsidies for nuclear generators.

ComEd customers in Illinois will see an average $19 monthly reduction to their electricity bills over the coming months, thanks to a policy in the state’s landmark climate bill.

At the time negotiations were underway for the 2021 Climate and Equitable Jobs Act, then-nuclear operator Exelon Corporation informed policymakers that it could not continue operating three of the state’s six nuclear stations profitably amid low energy prices. Rather than operate at a loss, Exelon would have opted to close the plants.

Closure would have been a major roadblock to Gov. JB Pritzker’s goals for a carbon-free future and could have resulted in significant energy shortfalls, creating reliability concerns and higher prices.

To avoid a crisis, lawmakers struck a deal.

Ratepayer bills were to include a small monthly surcharge to support the purchase of Carbon Mitigation Credits, or CMCs, to subsidize nuclear plants. The deal offered Exelon, now Constellation, the security of reliable income to meet its costs, while ensuring reliable carbon-free energy delivery for northern Illinoisians.

But it also imposed a ceiling. When the company’s revenues exceed a set threshold, either via federal subsidies or due to higher market prices, the excess flows back to ComEd customers.

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And as energy market prices have surged over the past few years, it turns out northern Illinois’ nuke plants haven’t needed the state’s help.

Instead, the program has provided a net benefit to ratepayers exceeding $1.8 billion since 2022, as ratepayers contributed $795 million to keep nuclear plants running but saw over $2.6 billion flow back to them.

The initiative has saved ComEd’s 3.8 million residential customers an average of $177 since it commenced, according to the Illinois Power Agency, which oversees procurement of the credits.

The deal was not about giving a “free lunch” to the nuclear plant operators, according to Rep. Ann Williams, D-Chicago, but about supporting the grid in a “responsible and equitable” way.

“And the end result proved that it was the right call on our part to include that kind of backstop so that, as we make investments in our generation supply, we make sure that it’s not a giveaway, and that consumers are made whole and kept whole,” Williams said.

‘Affordability being prioritized’

IPA Director Brian Granahan described the credits as the outcome of successful public policy, thanks to lawmakers working with nuclear plant operators.

ComEd customers receive electricity from the PJM Interconnection, the largest regional transmission organization in the nation. But as data center demand drives up energy rates for customers across the PJM region, it increases the price of energy. The price per megawatt-day at the December PJM capacity auction, for example, hit a record of $333.44 for 2027-28, 11.5 times higher than just three years prior.

While customer bills still rise, the CMC initiative partially offsets that cost for Illinois customers.

“We’re seeing something in Illinois that other states in the PJM region may not be seeing, in affordability being prioritized through this crediting coming through,” Granahan said. “Formed out of CEJA, the program has meaningfully supported clean energy in Illinois while insulating ratepayers from price spikes.”

ComEd customers have already seen higher than usual benefits this year, with over $580 million credited back on energy bills in the first two months of the year alone, according to the IPA.

The credits more than doubled between December and January, with $404 million credited to customers in January alone. That is part of an $803 million federal tax credit granted to Constellation under the Inflation Reduction Act, signed by former President Joe Biden in 2022.

It wasn’t always certain that federal subsidies received by nuclear plant operators would be considered revenue eligible for return to consumers, Granahan added, but Gov. JB Pritzker’s administration sought to ensure it would be in the CEJA provision.

“Thanks to the forward-looking policies in CEJA, Illinois is proving you can lower costs for consumers while strengthening clean, reliable energy,” a Pritzker spokesperson said.

Sarah Moskowitz, executive director of the Citizens Utility Board watchdog agency, called the credits “a testament to the value of thoughtful, pro-consumer energy legislation,” but said there is still work to be done.

“We have to build off this success and pass more pro-consumer legislation, including reforms that hold data centers accountable for their costs,” Moskowitz said.

What does this mean for bills?

For the first couple months of 2026, the federal subsidy returned to customers has translated into about a $13 monthly credit for residential ComEd customers. The remainder will continue to show up on customer bills through May.

And on top of the amount already coming in from the tax credits, high energy prices from early 2026 are going to give the credits an even bigger boost on April and May bills.

An average residential customer can expect to see around $19.40 credited on their April bill, according to ComEd. Though the May adjustments are not published yet, a ComEd spokesperson said they are “expected to still be more noticeable” due to the federal subsidy and higher energy and capacity prices.

Customers can find the credit listed as a Carbon-Free Energy Resource Adjustment under the Taxes, Fees & Other Credits section of their bills. Exact credit amounts will depend on energy usage.

The credits will be applied automatically, so customers don’t need to do anything extra to sign up for them. They will be received by most ComEd electric delivery customers, including those who purchase energy through an alternative energy supplier.

ComEd customers can expect to continue seeing credits during periods of high energy prices until they conclude in May 2027, as directed by statute.

Capitol News Illinois is a nonprofit, nonpartisan news service that distributes state government coverage to hundreds of news outlets statewide. It is funded primarily by the Illinois Press Foundation and the Robert R. McCormick Foundation.