Four percent for overpayments (3 percent for corporations).
One and one-half percent for the portion of a corporate overpayment exceeding $10,000.
Four percent for underpayments.
Six percent for large corporate underpayments.
Interest rates on overpayments and underpayments of tax are determined on a quarterly basis, in accordance with Section 6621 of the Internal Revenue Code.
“The federal short-term rate determined in accordance with Section 1274(d) during April 2017 is the rate published in Revenue Ruling 2017-11, 2017-19 IRB 1230, to take effect beginning May 1, 2017,” the IRS states. “The federal short-term rate, rounded to the nearest full percent, based on daily compounding determined during the month of April 2017 is 1 percent.”
So, 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, according to the IRS.
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 of a percentage point.