(a) Commencing on July 1 in all subsequent years, taxes on real and personal property may be paid and shall be accepted in three equal installments payable on the following dates:  September 15, February 15, and due in full on May 15.

(b) A penalty of eight percent shall be assessed on all delinquent taxes on the day following the due date of May 15. Interest of one percent per month shall be assessed on all outstanding balances beginning 30 days from the due date.