The IRS interest rates on overpayments and underpayments for the second quarter of 2023 are the same as the rates for the first quarter of 2023 (Rev. Rul. 2023-4). The rates beginning April 1, 2023, are:
Tax paid by self-employed persons to finance Social Security coverage. In 2007, there are two rates. A 12.4% rate applies to a taxable earnings base of $95,700 or less and a 2.9% rate applies to all net earnings.