The Internal Revenue Service (IRS) announced today that interest rates for the calendar quarter beginning October 1, 2026, will remain unchanged. This decision means taxpayers will see consistent rates for both overpayments and underpayments.
For individuals, the interest rate for both overpayments and underpayments will stay at 7% per year, compounded daily. Corporations will face a 6% rate for overpayments, with a reduced rate of 4.5% for the portion of an overpayment exceeding $10,000.
Regarding underpayments, corporations will be charged 7%, while large corporate underpayments will incur a higher rate of 9%. These quarterly rates are calculated based on the federal short-term rate, determined in July 2026, plus additional percentage points as specified by the Internal Revenue Code. Further details are available in Revenue Ruling 2026-15, which will be published in Internal Revenue Bulletin 2026-36 on August 31, 2026.