The U.S. Supreme Court has refused to hear an appeal from several utilities, including FirstEnergy and American Electric Power’s transmission arm, over a controversial fee known as the “RTO adder.” That move leaves in place a lower court ruling that said Ohio customers should not have been paying the charge.

The high court decided not to intervene, so the earlier decision stands. And that decision means lower bills going forward, and refunds for some customers.

The fee at the center of the fight was a 0.5% “adder” utilities were allowed to tack onto transmission costs if they joined a regional transmission organization, or RTO. Those groups help manage the flow of electricity over a multi-state grid. Federal regulators originally approved the incentive decades ago to encourage utilities to join.

But in Ohio, joining an RTO isn’t optional, the state law requires it. The Sixth Circuit Court of Appeals ruled that because the utilities didn’t really have a choice, the extra “incentive” payment wasn’t justified. It just made bills higher.

The Ohio Consumers’ Counsel calls the outcome a “huge win” for Ohioans, estimating more than $400 million in savings statewide through 2031 once the fee is removed.

Here’s what that means at the household level:

• FirstEnergy and Duke Energy Ohio customers are in line for refunds of the RTO adder they’ve paid since February 2022, when the Consumers’ Counsel first challenged the charge.
• The exact dollar amount per customer and the exact timing haven’t been finalized yet. Regulators and the utilities still have to work out how the money will be calculated and returned.
• AES Ohio and AEP Ohio customers won’t see refunds from this case. AES never got permission to charge the adder, and federal regulators blocked AEP from collecting it in a 2022 decision.

Going forward, removing the adder should trim what utilities can bill for transmission, which is one piece of your electric bill. It’s not going to zero out your charges, but it does mean hundreds of millions of dollars that would have gone to utilities will instead stay with customers.

For now, you don’t have to do anything to claim a refund. Credits or checks, when they’re approved, are expected to be handled automatically through the normal billing process.