Okla. Stat. tit. 11 § 36-216
Assessments in conformity to the appraisement and apportionment, as corrected and confirmed by the governing body, shall be payable in ten equal annual installments, and shall bear interest at the rate of not to exceed thirteen percent (13%) per annum until paid, payable in each year at such time as the several installments are made payable. The governing body, by ordinance and by referring to the assessment roll as confirmed, shall levy assessments in accordance with the assessment roll as confirmed against the several lots and tracts of land liable therefor. The ordinance shall provide that the owners of the property so assessed shall have the privilege of paying the amounts of their respective assessments without interest within thirty (30) days after the date of the publication of the assessing ordinance. The special assessments, and each installment thereof and the interest thereon, are hereby declared to be a lien against the lots and tracts of land so assessed from the date of the publication of the ordinance levying the same, coequal with the lien of other taxes and prior and superior to all other liens against such lots or tracts of land. The lien shall continue as to unpaid installments and interest until the assessments and interest thereon shall be fully paid, but unmatured installments shall not be deemed to be within the terms of any general convenant or warranty.
Okla. Stat. tit. 11, § 36-216