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 Oregon, 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 the contract between the parties or, if there is no contract rate, by the legal rate set by statute. Oregon law specifies that prejudgment interest rates are typically set at 9% per annum unless a different rate is contracted for in writing. Post-judgment interest is the interest that accrues on the amount of the judgment from the date the judgment is entered until it is paid. In Oregon, the post-judgment interest rate is also generally set at 9% per annum, as specified in ORS 82.010. It is important to note that these rates are subject to change by the legislature, and an attorney can provide the most current rates and assist with the calculation of interest on judgments.