The IRS has announced that the interest rates for the calendar quarter beginning October 1, 2017, will be 4 percent for overpayments (3 percent in the case of a corporation), 4 percent for underpayments and 6 percent for large corporate underpayments. The interest rate for the portion of a corporate overpayment exceeding $10,000 is 1.5 percent. The interest rates are computed by using the federal short-term rate based on daily compounding determined during July 2017.The Internal Revenue Code provides that the rate of interest is to be 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 of a percentage point.IR-2017-147Rev. Rul. 2017-18Other References:Code Sec. 6601CCH Reference – 2017FED ¶174.01CCH Reference – 2017FED ¶175.01CCH Reference – 2017FED ¶175.30CCH Reference – ETR ¶102CCH Reference – ETR ¶50,615.01Code Sec. 6621CCH Reference – 2017FED ¶39,455.021CCH Reference – FINH ¶21,685.01CCH Reference – FINH ¶21,685.30Code Sec. 6622CCH Reference – 2017FED ¶39,465.01Tax Research ConsultantCCH Reference – TRC ACCTNG: 33,204.15CCH Reference – TRC PENALTY: 9,152Login to read more tax news on CCH® AnswerConnect or CCH® Intelliconnect®.Not a subscriber? Sign up for a free trial or contact us for a representative.