By Jack Money Business Writer jmoney@oklahoman.comState regulators on Wednesday ordered Public Service Co. of Oklahoma to return $428 million to its customers. The funds are savings the company received through the Tax Cuts and Jobs Act of 2017. Corporation commissioners approved an order requiring a return of that amount in a case brought before the agency by Attorney General Mike Hunter. A commission spokesman on Wednesday said PSO has told the agency it expects its average residential customer will save $6.08 a month during 2018 as a result of the order approved on Wednesday. The decision requires the refund in addition to a $30 million reduction in rates it had ordered the utility to make in January, also to compensate its customers for the tax cut. The utility is authorized to collect its expected tax liabilities from customers as part of regular bills.