Revenue Ruling 2021-10 provides interest rates for underpayments and overpayments for the 3rd quarter 2021. The rates for interest determined under Section 6621 of the code for the calendar quarter beginning July 1, 2021, will be 3 percent for overpayments (2 percent in the case of a corporation), 3 percent for underpayments, and 5 percent for large corporate underpayments. The rate of interest paid on the portion of a corporate overpayment exceeding $10,000 will be 0.5 percent.

Revenue Ruling 2021-10 will be in IRB:  2021-25, dated June 21, 2021.