On 2 March 2021, the Internal Revenue Service announced that interest rates for the calendar quarter beginning April 1, 2021. The rates are unchanged from the previous quarter.

The rates are:

  • 3% for overpayments (2% in the case of a corporation);
  • 0.5% for the portion of a corporate overpayment exceeding $10,000;
  • 3% for underpayments; and
  • 5% 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 January 2021 to take effect February 1, 2021, based on daily compounding.