Okla. Stat. tit. 11, § 11-37-225: Due date of first installment - Payment of assessments

- Interest on delinquent installments.

A. The first installment of the assessment, together with

interest upon the whole assessment from the date of the passage of

the assessing ordinance to the first day of the next September,

shall be due and payable in cash on or before the first day of

September next succeeding the passage of the assessing ordinance. If

the assessing ordinance is not passed prior to the first day of July

in any year, the first installment of the assessment shall be due

and payable in cash with interest from the date of the passage of

the assessing ordinance to the first day of September of the

following year.

B. The assessments shall be payable as the several installments

become due, together with the interest thereon, to the municipal

clerk, who shall give proper receipts for the payments, and credit

the payments upon the Assessment Record. In case any installment or

interest is not paid when due, the installment so matured and unpaid

and the unpaid interest thereon shall draw interest at the rate of

twelve percent (12%) per annum from maturity until paid, except as

otherwise provided.