The Internal Revenue Service has announced that interest rates will remain the same for the calendar quarter beginning October 1, 2017. The interest rates are as follows: four percent for overpayments (three percent in the case of a corporation); four percent for underpayments; six percent for large corporate underpayments; and one and one-half percent for the portion of a corporate overpayment exceeding $10,000.
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 three percentage points. Generally, in the case of a corporation, the underpayment rate is the federal short-term rate plus three percentage points and the overpayment rate is the federal short-term rate plus two percentage points. The rate for large corporate underpayments is the federal short-term rate plus five 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 a percentage point.
These interest rates are computed from the federal short-term rate based on daily compounding determined during July 2017 (IR-2017-147, September 8, 2017; Rev. Rul. 2017-18, I.R.B. No. 2017-39, September 25, 2017).