Section 8A.514 - Vouchers - interest - payment of claims1. Before a warrant or its equivalent is issued for a claim payable from the state treasury, the department shall file an itemized voucher showing in detail the items of service, expense, item furnished, or contract for which payment is sought. However, the director may authorize the prepayment of claims when the best interests of the state are served under rules adopted by the director. The claimant's original invoice shall be attached to a department's approved voucher. The director shall adopt rules specifying the form and contents for invoices submitted by a vendor to a department. The requirements apply to acceptance of an invoice by a department. A department shall not impose additional or different requirements on submission of invoices than those contained in rules of the director unless the director exempts the department from the invoice requirements or a part of the requirements upon a finding that compliance would result in poor accounting or management practices.2. Vouchers for postage, stamped envelopes, and postal cards may be audited as soon as an order for them is entered.3. The departments, the general assembly, and the courts shall pay their claims in a timely manner. If a claim for services, supplies, materials, or a contract which is payable from the state treasury remains unpaid after sixty days following the receipt of the claim or the satisfactory delivery, furnishing, or performance of the services, supplies, materials, or contract, whichever date is later, the state shall pay interest at the rate of one percent per month on the unpaid amount of the claim. This subsection does not apply to claims against the state under chapters 25 and 669 or to claims paid by federal funds. The interest shall be charged to the appropriation or fund to which the claim is certified. Departments may enter into contracts for goods or services on payment terms of less than sixty days if the state may obtain a financial benefit or incentive which would not otherwise be available from the vendor. The department, in consultation with other affected departments, shall develop policies to promote consistency and fiscal responsibility relating to payment terms authorized under this subsection. The director shall adopt rules under chapter 17A relating to the administration of this subsection.