Interest Rates - IRS

Interest Rates for Q1, Q2 and Q3 for 2013 will continue to be charged as follows:
3% for overpayments (2% for corporations)
3% for underpayments
5% for large corporate underpayments
0.5% for the portion of a corporate overpayment in excess of $10k.
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. Further, the federal short-term rate that applies during the third month following the taxable year also applies when determining estimated tax underpayments during the first 15 days of the fourth month following the taxable year