Irs Interest Rates 2025 Calculator. It is mainly intended for residents of the u.s. Irs and state quarterly interest rates table.

The highest annual interest rate of 5.03%—which is from the december 2025 rate and is higher than the november 2025 rate of 4.45% and the default 5.0% (see above). The irs interest rate on unpaid taxes and tax refunds for individuals is 8% for all of 2025 and 7% for the first quarter of 2025 (the rate is adjusted on a quarterly basis).