N.D. Cent. Code § 13-01.1-01: Prompt payment required

Every state agency, political subdivision, or school district, which acquires property or services pursuant to a contract with a business shall pay for each complete delivered item of property or service on the date required by contract between such business and agency or, if no date for payment is specified by contract, within forty-five days after receipt of the invoice covering the delivered items or services. The acquisition of property includes the rental of real or personal property.