The parties involved in the OG&E rate case have reached a $64 million rate reduction settlement agreement, the state attorney general announced Wednesday.

Attorney General Mike Hunter said this settlement will result in lower utility bills for OG&E customers beginning in July.

Customers will also receive a one-time refund as a result of the $18.5 million federal corporation income tax cut. 

This is the largest rate reduction ever for an Oklahoma energy utility, the attorney general's office said Wednesday.

Residential OG&E customers will see an average approximate reduction of $18.71 on their July bills. Each subsequent month, the average savings for a standard residential customer will be approximately $4.44.

Business and government agency customers will see a total savings of about $32 million.

"This historic reduction represents the largest rate reduction ever received by customers of an Oklahoma energy utility and will put real money back in the pockets of hard-working Oklahomans," Hunter said in a news release.

All parties supported the settlement, the attorney general's office said.

A majority of the three-member state Corporation Commission must approve the settlement agreement before it can go into effect.