Mo. Rev. Stat. § 242.580
Current with changes from the 2023 Legislative Session
All taxes provided for in sections 242.010 to 242.690 remaining unpaid after December thirty-first of the year for which said taxes were levied shall become delinquent and bear a penalty of one percent per month on the amount of said taxes from date of delinquency until paid. In computing said penalty each fractional part of a month shall be counted as a full month.
§ 242.580, RSMo
RSMo 1939 § 12343