# Treas. Reg. § 53.6601-1: Interest on underpayment, nonpayment, or extensions of time for payment, of tax.

Source: eCFR as of 2026-10-19 <https://www.ecfr.gov/current/title-26/section-53.6601-1>. Interprets 26 U.S.C. § 6601.

For regulations concerning interest on underpayment, nonpayment, or extensions of time for payment of tax, see § 301.6601-1 of this chapter (Regulations on Procedure and Administration).