Okla. Stat. tit. 16 § 11A
All contracts for deed for purchase and sale of real property made for the purpose or with the intention of receiving the payment of money and made for the purpose of establishing an immediate and continuing right of possession of the described real property, whether such instruments be from the debtor to the creditor or from the debtor to some third person in trust for the creditor, shall to that extent be deemed and held mortgages, and shall be subject to the same rules of foreclosure and to the same regulations, restraints and forms as are prescribed in relation to mortgages. No foreclosure shall be initiated, nor shall the court allow such proceedings, unless the documents have been filed of record in the county clerk's office, and mortgage tax paid thereon, in the amount required for regular mortgage transactions. Provided, however, mutual help and occupancy agreements executed by an Indian housing authority created pursuant to Section 1057 of Title 63 of the Oklahoma Statutes shall not be considered to be mortgages or contracts for deed under the provisions of this section.
Okla. Stat. tit. 16, § 11A