Mo. Rev. Stat. § 34.055

34.055. State to pay late charges for supplies and services, when, rate — vendor to apply, exception — energy assistance program for persons of low income, recipients exempt from interest charges. — 1. Except as otherwise provided in section 8.960 , all invoices for supplies and services purchased by the state, duly approved and processed, shall be subject to interest charges or late payment charges as provided in this section.

2. After the forty-fifth day following the later of the date of delivery of the supplies and services or the date upon which the invoice is duly approved and processed, interest retroactive to the thirtieth day shall be paid on any unpaid balance, except balances for services provided by a gas corporation, electrical corporation, water corporation, or sewer corporation which has received authorization from the public service commission to impose late payment charges on delinquent utility bills, upon application of the vendor thereof. The rate of such interest shall be three percentage points above the average predominant prime rate quoted by commercial banks to large businesses, as determined by the Board of Governors of the Federal Reserve System.

3. The state shall be liable for late payment charges on any delinquent bill for services purchased by the state from a gas corporation, electrical corporation, water corporation, or sewer corporation which has received authorization from the public service commission to impose late payment charges on delinquent utility bills. The rate of such late payment charges shall be as established for each such corporation by order of the public service commission, but bills rendered to the state shall not be considered delinquent until thirty days after rendition of the bill by the corporation.

4. Any such interest charges or late payment charges shall be paid from appropriations which were made for the fiscal year in which the supplies or services were delivered to the respective departments purchasing such supplies or services. The commissioner of administration shall be responsible for the timely implementation of this section and all officers, departments, institutions and agencies of state government shall fully cooperate with the commissioner of administration in the implementation of this section. No late payment penalty shall be assessed against, nor payable by, the state unless pursuant to the provisions of this section.

5. Notwithstanding any other provision of this section, recipients of funds from the low-income energy assistance program shall be exempt from interest charges imposed by such section for the duration of the recipient's participation in the program.

(L. 1985 S.B. 90, A.L. 1987 S.B. 411, A.L. 1990 S.B. 808 & 672, A.L. 2022 S.B. 758)