Okla. Stat. tit. 17, § 284

In its review and examination of an application by a utility to change its rates and charges pursuant to Sections 137, 152 or 158.27 of Title 17 of the Oklahoma Statutes, and in any order resulting therefrom, the Corporation Commission shall give effect to known and measurable changes occurring or reasonably certain to occur within six (6) months of the end of the test period upon which the rate review is based.