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Treasury Regulations · 26 CFR Part 301

Subpart ECFR612dc3cd920dcce. Interest

Regulation text, no changes From the eCFR, current as of October 15, 2026. The eCFR is an authoritative but unofficial editorial compilation of the Code of Federal Regulations; the official text is the annual CFR on govinfo. Compare it with Title 26 on ecfr.gov (external site) or the official annual CFR on govinfo (external site).

  1. Interest on Underpayments §§ 301.6601-1 to 301.6622-1

    1. § 301.6601-1 Interest on underpayments.
    2. § 301.6602-1 Interest on erroneous refund recoverable by suit.
    3. § 301.6611-1 Interest on overpayments.
    4. § 301.6621-1 Interest rate.
    5. § 301.6621-2T Questions and answers relating to the increased rate of interest on substantial underpayments attributable to certain tax motivated transactions (temporary).
    6. § 301.6621-3 Higher interest rate payable on large corporate underpayments.
    7. § 301.6622-1 Interest compounded daily.