IR-2006-143, Sept. 11, 2006 WASHINGTON — The Internal Revenue Service today announced there will be no change in the interest rates for the calendar quarter beginning October 1, 2006. The interest rates are as follows: eight (8) percent for overpayments [seven (7) percent in the case of a corporation]; eight (8) percent for underpayments; ten (10) percent for large corporate underpayments; and five and one-half (5.5) 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 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 announced today are computed from the federal short-term rate based on daily compounding determined during July 2006. Rev. Rul. 2006-49, below, announcing the new rates of interest, will also appear in Internal Revenue Bulletin No. 2006-40, dated October 2, 2006. Related Item: Rev. Rul. 2006-49 PDF Subscribe to IRS Newswire