On 25 August 2023, the U.S. Internal Revenue Service announced the interest rates for overpaid and underpaid taxes for the fourth quarter of 2023. Accordingly, the interest rates will increase for the calendar quarter beginning 1 October 2023.

For individuals, the rate for overpayments and underpayments will be 8% per year, compounded daily. Here is a complete list of the new rates:

  • 8% for overpayments (payments made in excess of the amount owed), 7% for corporations.
  • 5.5% for the portion of a corporate overpayment exceeding $10,000.
  • 8% for underpayments (taxes owed but not fully paid).
  • 10% for large corporate underpayments.

Under the Internal Revenue Code, the rate of interest is determined on a quarterly basis. For taxpayers other than corporations, the overpayment and underpayment rate is the federal short-term rate plus 3 percentage points.

Generally, in the case of a corporation, the underpayment rate is the federal short-term rate plus 3 percentage points and the overpayment rate is the federal short-term rate plus 2 percentage points. The rate for large corporate underpayments is the federal short-term rate plus 5 percentage points. The rate on the portion of a corporate overpayment of tax exceeding $10,000 for a taxable period is the federal short-term rate plus one-half (0.5) of a percentage point.

The interest rates are computed from the federal short-term rate determined during July 2023.