Oklahoma Administrative Code
Title 260 - Office of Management and Enterprise Services
Chapter 10 - Prompt Payment to Vendors and Employees of the State of Oklahoma Through the Payment of Interest on Late Payments
Subchapter 3 - Vendor and Employee Interest Claim Procedures
Section 260:10-3-2 - Calculation of 45-day payment period

(1) The clock shall begin to run thirty (30) days after the later of the date of proper invoice, the receipt of a proper invoice by the agency, or the receipt of the goods or services in an acceptable condition specified by the contract or purchase order, or in the case of employee travel claims, the clock shall begin to run thirty (30) days after the date of receipt of a proper claim by the authorized office or official of the agency.

(2) The clock shall end when the agency makes payment.