Okla. Stat. tit. 68, § 500.31

A. Each person blending untaxed materials, including blendstocks, fuel grade ethanol and additives with motor fuels as to which tax has already been paid or accrued shall remit the tax imposed by this act. B. Any consumer liable for the tax payable under subsection A of this section shall remit the tax directly to the Commission within thirty (30) days of the blending event in accordance with regulations promulgated by the Commission.