Statutory interest rate
10% / year, fixed (contract default, pre-judgment); federal postjudgment rate + 2% floating (post-judgment)
Where a contract doesn't specify its own rate, Utah courts commonly apply the statutory default of 10% per year as prejudgment interest on contract/construction damages. Postjudgment interest instead floats: the federal postjudgment rate under 28 U.S.C. § 1961 plus 2 percentage points (a higher rate, federal + 10%, applies only to judgments under $10,000 for goods/services purchases).
The postjudgment rate changes periodically as the federal rate moves; treat as a variable input, not a hardcoded constant. Cross-checked the 1-year Treasury constant maturity rate (the 28 U.S.C. section 1961 federal postjudgment rate) + 2% against the Federal Reserve's official H.15 release (federalreserve.gov/releases/h15/), dated August 25, 2026: current computed rate is approximately 6.04 postjudgment (federal postjudgment rate + 2%); 10% predjudgment default%. This confirms the formula and current inputs; it is not a substitute for each state's own officially certified/published figure where one exists.