Tax overpayment and underpayment interest rates will remain unchanged for the first quarter of 2021.

For noncorporate taxpayers, the rate for both underpayments and overpayments for the quarter starting Jan. 1 will be 3%. The 3% rate also applies to estimated tax underpayments for the first quarter of 2021. For corporations, the overpayment rate will be 2%, with a 0.5% rate applicable to overpayments exceeding $10,000. The underpayment rate for corporations will be 3%, except for large corporate underpayments, which will be 5%. (IRS Rev. Rul. 2020-28)