Okla. Stat. tit. 68 § 248
In addition to information required on any state tax return or report prescribed by the Oklahoma Tax Commission, upon request or demand for production of information by the Commission, or its duly authorized agent, a state taxpayer shall furnish any information deemed necessary to determine the amount of state tax liability. Notwithstanding Section 205 of this title the Commission shall have the power to compel the production of books, records or papers of any person, firm, association, partnership, corporation or other legal entity regarding the business, property, assets or effects of any Oklahoma taxpayer which may be necessary to a determination of state tax liability of such taxpayer, including any books, records or papers necessary to obtain or verify information necessary for resolution of a protest by a taxpayer to an assessment of tax or additional tax or to the resolution of a claim for refund filed by a taxpayer. If the information is deemed confidential or proprietary by the person, firm, association, partnership, corporation or other legal entity, no production can be compelled pending a hearing on the nature and extent of the production of privileged and confidential information.
Okla. Stat. tit. 68, § 248