Interest rates are compensation for the time-value of money, and are calculated on judgments (the amount of money one party to a lawsuit is ordered to pay another party) based on the applicable state or federal statutes. There are often different interest rates set by law for prejudgment interest (the interest on the amount owed before the judgment) and post-judgment interest (the interest on the amount owed after the judgment). The calculation of prejudgment and post-judgment interest rates vary from state to state (and in federal court), and require a careful analysis of the statutes.

In Oklahoma, interest rates on judgments are governed by state statutes, which set forth the rates for both prejudgment and post-judgment interest. Prejudgment interest is the interest accrued from the time the money is owed until a judgment is entered, and its rate can be determined by contract or statute if no contract exists. As of the knowledge cutoff in 2023, Oklahoma Statutes Title 12, Section 727.1 generally allows for prejudgment interest at a rate not to exceed the average U.S. Treasury Bill rate of the preceding calendar year plus 4%. Post-judgment interest is the interest that accrues after a judgment has been entered by the court. In Oklahoma, post-judgment interest rates are set by statute and are subject to change. According to Oklahoma Statutes Title 12, Section 727, the post-judgment interest rate is based on the average U.S. Treasury Bill rate of the preceding calendar year plus 2%. It is important for parties involved in litigation to consult with an attorney to understand the specific rates that may apply to their case and any recent changes to the law.