Okla. Stat. tit. 68 § 602
It is hereby declared to be the purpose of Section 601 et seq. of this title to levy a tax on those importing gasoline and diesel fuel into this state in the fuel supply tanks of vehicles being used on the highways of this state for commercial purposes, as a just and reasonable contribution to the cost of constructing, maintaining and policing such highways incident to the use thereof by such persons, and to the end that the highway users shall pay to this state an equal amount in taxes as is paid by other commercial highway users who use gasoline and diesel fuel on which the motor fuel excise tax has been paid to this state. The revenues, including interest and penalties, collected under the provisions of this article, shall be apportioned monthly in the manner and in the same proportion for the same purposes as the revenue collected pursuant to the Motor Fuel Tax Code is apportioned.
Provided, in the event that collections are insufficient for the monthly payment of motor fuel taxes to other states or jurisdictions in accordance with the International Fuel Tax Agreement, the Oklahoma Tax Commission shall transfer to the Corporation Commission the sum necessary for payment in full from current diesel fuel tax collections. Such transfer shall occur within five (5) working days of the request by the Corporation Commission.
Okla. Stat. tit. 68, § 602