Montana Title 17. State Finance § 17-8-242. Interest assessed on amounts due

(1) Except as provided in 17-8-244, a state agency shall pay simple interest at the rate of 0.05% each day on amounts due for supplies and services received if the agency fails to make timely payment.

(2) For purposes of this section, payment is timely if a warrant is mailed or is otherwise made available to the payee when due and for the amount specified in the applicable contract or agreement. If no date is specified in the applicable contract or agreement, payment is timely if paid within 30 days after receipt of a properly completed invoice, addressed to the payer agency, or receipt of the supplies or services by the agency, whichever is later.