By Jack MoneyBusiness writer jmoney@oklahoman.comThe Oklahoma Corporation Commission on Tuesday signed off on a stipulated agreement that will return about $27 million to Oklahoma Natural Gas customers during the coming year. The adjustments are being made as part of an annual review of a performance-based rate agreement the agency uses to regulate the company, a division of One Gas. Under the agreement, the rates ONG can charge are tied to various performance metrics, including customer satisfaction rates and outage percentages that typically are reviewed annually. Under that type of regulation, justifiable subsequent rate changes only are authorized when those reviews find the regulated entity met its prescribed performance standards. Officials said Tuesday some of what will be returned to its customers as part of this week’s agreement will compensate the company’s customers for overcollections that provided the utility with a better return on investment than the existing agreement allows. Officials said the company's residential customers will see credits on their bills during the next 12 months of about $1.47 monthly to account for those over collections. Commercial, nonresidential transport and transport-only customers also will get credits.Read more on NewsOK.com