Okla. Stat. tit. 68, § 68-722: Tax credit on special fuels consumed outside State -

Application and procedure.

Any person licensed as a special fuel dealer or special fuel

user shall be entitled to a credit equivalent to the tax rate per

gallon on all special fuels upon which the Oklahoma special fuel tax

has been paid and which has thereafter been consumed in motor

vehicles outside the State of Oklahoma. When the amount of credit

herein provided to which the dealer or user is entitled for any

calendar month exceeds the amount of tax for which such dealer or

user is liable for special fuels consumed in Oklahoma in such

vehicles during the same month, such excess shall, under regulations

promulgated by the Oklahoma Tax Commission, be allowed as a credit

against the tax for which such dealer or user would be otherwise

liable for any of the succeeding months; or, upon claim filed with

the Oklahoma Tax Commission within one (1) year from the first day

of any calendar month in which said special fuel was used, such

excess may be refunded. Application for refund must be supported by

evidence of the mileage traveled and the gallonage consumed and

satisfactory evidence of the tax-paid purchases. Refund vouchers

shall be paid from current collections derived from the tax levied

under which the tax refund claims have been allowed, and a portion

of such current collections as are necessary to pay such refund is

hereby appropriated.