Okla. Stat. tit. 19 § 882
The clerk of said district shall no earlier than the first day in July and no later than the tenth day in July in each year certify the installments of assessments coming due on the first day of September in said year, together with interest on the same, and on all unmatured installments, to the county treasurer of said county, to be collected as other taxes; which money, when collected by the county treasurer shall, with interest thereon at the rate of six percent (6%) per annum, until paid, be paid to the clerk of said sewer improvement district. Provided, that no such certification shall be made to the county treasurer unless the clerk of said district shall have sent a notice of the nature and amount of the assessments by restricted delivery mail on or before June 1 of said year to the last-known address of the owner of the assessed property. Provided, that in case any special assessment bond or coupon provided for in Section 881 of this title becomes delinquent, then such bond or coupon shall draw interest as a penalty after delinquency at the rate of twelve percent (12%) per annum, and when collected six percent (6%) of such interest or penalty shall be paid to the then holder of such bond or coupon and six percent (6%) thereof shall be paid to the sewer improvement district which issued said bond, which amount shall go to the general fund of said sewer improvement district. Such special assessments and each installment thereof and the interest and penalty 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 ad valorem taxes, all other taxes and special assessments, and prior and superior to all other titles and liens against such lots or tracts of land, and such lien shall continue as to unpaid installments, interest and penalty until such installments, interest and penalty thereof shall be fully paid, but unmatured installments shall not be deemed to be within the terms of any general covenant of warranty.
If any installment of assessment shall remain unpaid for six (6) months after the same is due, the holder of any bond or coupon, issued under the provisions of this act, may institute an action in the district court to foreclose the lien of such assessment, stating in the petition generally the ownership of such bond, or coupon, describing the property assessed, the nature of the improvement, the amount of the unpaid assessment and interest, and penalty, and praying for the foreclosure of such lien. All bonds and coupons issued in said district and held by plaintiff may be included in one action. Upon the filing of such action, all unmatured installments of assessments shall become immediately due and payable and the lien of such assessments foreclosed in such action. Summons shall be issued on such petition as in other civil actions and the cause tried by the district court. Judgment shall be entered for the amount of such unpaid assessments, and installments, together with penalty thereon at the rate of twelve percent (12%) per annum from the due date of each installment, and reasonable attorney's fees. The judgment shall bear interest at the rate of six percent (6%) per annum.
In the event said judgment, together with interest and costs, including attorney's fee, is not paid within thirty (30) days from its date, an order of sale shall issue by the clerk of said court, directed to the sheriff of the county, to sell said real estate in manner and form as in case of said real estate, without appraisement. Such judgment shall carry the costs of the action, including a reasonable attorney's fee to plaintiff, together with the costs of such sale; and upon the payment of such judgment, to the sheriff or court clerk, the amount thereof exclusive of costs and attorney's fees shall be paid to the county treasurer. Such judgment shall provide for the sale of said real estate, subject to existing general ad valorem taxes and special assessments. All owners and incumbrancers shall be made parties defendant in such action. The entire unpaid assessment, as to each tract, shall be foreclosed. All such actions to foreclose said assessment shall be commenced within three (3) years from the maturity date of the last installment thereof.
Okla. Stat. tit. 19, § 882