The Mississippi Public Service Commission voted 3-0 Tuesday to comply with a state Supreme Court order that found illegal the 2013 rate increase for the $6.2 billion plant.
The unit of Atlanta-based Southern Co. must roll back the 18 percent increase starting with the August billing cycle.
Commissioners say they’ll vote on a refund plan in August. Customers can choose a one-time refund check or credits against future bills over a longer period. Mississippi Power could have to borrow to pay refunds.