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:
7% for overpayments (6% in the case of a corporation);
4.5% for the portion of a corporate overpayment exceeding $10,000;