That annual improvement assessments for each improvement shall be made by the governing body when the levy of municipal property taxes is made; and such improvement assessments shall be due at the same time, or times, the municipal property taxes are due, and shall be subject to the same penalties and accrual of interest in the event of non-payment as in the case of municipal property taxes. The governing body may permit owners of benefited property to pay improvement assessments in equal monthly installments, the first installment to be due and payable when the improvement assessment is due; in this event any monthly payment shall be delinquent 30 days after it is due and payable, and the whole balance of the annual improvement assessment shall thereupon become delinquent and be subject to all penalties and interest as provided in this Act (Article.) [As added by Priv. Acts 1970, ch. 276, § 12]