# 26 U.S.C. § 6601: Interest on underpayment, nonpayment, or extensions of time for payment, of tax

Source: OLRC release point 119-134 <https://uscode.house.gov/us/usc/119-134/t26/s6601>. Cite pinpoints as 26 U.S.C. § 6601(a)(1).

## § 6601(a) General rule

If any amount of tax imposed by this title (whether required to be shown on a return, or to be paid by stamp or by some other method) is not paid on or before the last date prescribed for payment, interest on such amount at the underpayment rate established under section 6621 shall be paid for the period from such last date to the date paid.

## § 6601(b) Last date prescribed for payment

For purposes of this section, the last date prescribed for payment of the tax shall be determined under chapter 62 with the application of the following rules:

**§ 6601(b)(1) Extensions of time disregarded.** The last date prescribed for payment shall be determined without regard to any extension of time for payment or any installment agreement entered into under section 6159.

**§ 6601(b)(2) Jeopardy.** The last date prescribed for payment shall be determined without regard to any notice and demand for payment issued, by reason of jeopardy (as provided in chapter 70), prior to the last date otherwise prescribed for such payment.

**§ 6601(b)(3) Accumulated earnings tax.** In the case of the tax imposed by section 531 for any taxable year, the last date prescribed for payment shall be deemed to be the due date (without regard to extensions) for the return of tax imposed by subtitle A for such taxable year.

**§ 6601(b)(4) Last date for payment not otherwise prescribed.** In the case of taxes payable by stamp and in all other cases in which the last date for payment is not otherwise prescribed, the last date for payment shall be deemed to be the date the liability for tax arises (and in no event shall be later than the date notice and demand for the tax is made by the Secretary).

## § 6601(c) Suspension of interest in certain income, estate, gift, and certain excise tax cases

In the case of a deficiency as defined in section 6211 (relating to income, estate, gift, and certain excise taxes), if a waiver of restrictions under section 6213(d) on the assessment of such deficiency has been filed, and if notice and demand by the Secretary for payment of such deficiency is not made within 30 days after the filing of such waiver, interest shall not be imposed on such deficiency for the period beginning immediately after such 30th day and ending with the date of notice and demand and interest shall not be imposed during such period on any interest with respect to such deficiency for any prior period.

## § 6601(d) Income tax reduced by carryback or adjustment for certain unused deductions

**§ 6601(d)(1) Net operating loss or capital loss carryback.** If the amount of any tax imposed by subtitle A is reduced by reason of a carryback of a net operating loss or net capital loss, such reduction in tax shall not affect the computation of interest under this section for the period ending with the filing date for the taxable year in which the net operating loss or net capital loss arises.

**§ 6601(d)(2) Foreign tax credit carrybacks.** If any credit allowed for any taxable year is increased by reason of a carryback of tax paid or accrued to foreign countries or possessions of the United States, such increase shall not affect the computation of interest under this section for the period ending with the filing date for the taxable year in which such taxes were in fact paid or accrued, or, with respect to any portion of such credit carryback from a taxable year attributable to a net operating loss carryback or a capital loss carryback from a subsequent taxable year, such increase shall not affect the computation of interest under this section for the period ending with the filing date for such subsequent taxable year.

**§ 6601(d)(3) Certain credit carrybacks.**

**§ 6601(d)(3)(A) In general.** If any credit allowed for any taxable year is increased by reason of a credit carryback, such increase shall not affect the computation of interest under this section for the period ending with the filing date for the taxable year in which the credit carryback arises, or, with respect to any portion of a credit carryback from a taxable year attributable to a net operating loss carryback, capital loss carryback, or other credit carryback from a subsequent taxable year, such increase shall not affect the computation of interest under this section for the period ending with the filing date for such subsequent taxable year.

**§ 6601(d)(3)(B) Credit carryback defined.** For purposes of this paragraph, the term “credit carryback” has the meaning given such term by section 6511(d)(4)(C).

**§ 6601(d)(4) Filing date.** For purposes of this subsection, the term “filing date” has the meaning given to such term by section 6611(f)(4)(A).

## § 6601(e) Applicable rules

Except as otherwise provided in this title—

**§ 6601(e)(1) Interest treated as tax.** Interest prescribed under this section on any tax shall be paid upon notice and demand, and shall be assessed, collected, and paid in the same manner as taxes. Any reference to this title (except subchapter B of chapter 63, relating to deficiency procedures) to any tax imposed by this title shall be deemed also to refer to interest imposed by this section on such tax.

**§ 6601(e)(2) Interest on penalties, additional amounts, or additions to the tax.**

**§ 6601(e)(2)(A) In general.** Interest shall be imposed under subsection (a) in respect of any assessable penalty, additional amount, or addition to the tax (other than an addition to tax imposed under section 6651(a)(1) or 6653 or under part II of subchapter A of chapter 68) only if such assessable penalty, additional amount, or addition to the tax is not paid within 21 calendar days from the date of notice and demand therefor (10 business days if the amount for which such notice and demand is made equals or exceeds $100,000), and in such case interest shall be imposed only for the period from the date of the notice and demand to the date of payment.

**§ 6601(e)(2)(B) Interest on certain additions to tax.** Interest shall be imposed under this section with respect to any addition to tax imposed by section 6651(a)(1) or 6653 or under part II of subchapter A of chapter 68 for the period which—

**§ 6601(e)(2)(B)(i)** begins on the date on which the return of the tax with respect to which such addition to tax is imposed is required to be filed (including any extensions), and

**§ 6601(e)(2)(B)(ii)** ends on the date of payment of such addition to tax.

**§ 6601(e)(3) Payments made within specified period after notice and demand.** If notice and demand is made for payment of any amount and if such amount is paid within 21 calendar days (10 business days if the amount for which such notice and demand is made equals or exceeds $100,000) after the date of such notice and demand, interest under this section on the amount so paid shall not be imposed for the period after the date of such notice and demand.

## § 6601(f) Satisfaction by credits

If any portion of a tax is satisfied by credit of an overpayment, then no interest shall be imposed under this section on the portion of the tax so satisfied for any period during which, if the credit had not been made, interest would have been allowable with respect to such overpayment. The preceding sentence shall not apply to the extent that section 6621(d) applies.

## § 6601(g) Limitation on assessment and collection

Interest prescribed under this section on any tax may be assessed and collected at any time during the period within which the tax to which such interest relates may be collected.

## § 6601(h) Exception as to estimated tax

This section shall not apply to any failure to pay any estimated tax required to be paid by section 6654 or 6655.

## § 6601(i) Exception as to Federal unemployment tax

This section shall not apply to any failure to make a payment of tax imposed by section 3301 for a calendar quarter or other period within a taxable year required under authority of section 6157.

## § 6601(j) 2-percent rate on certain portion of estate tax extended under section 6166

**§ 6601(j)(1) In general.** If the time for payment of an amount of tax imposed by chapter 11 is extended as provided in section 6166, then in lieu of the annual rate provided by subsection (a)—

**§ 6601(j)(1)(A)** interest on the 2-percent portion of such amount shall be paid at the rate of 2 percent, and

**§ 6601(j)(1)(B)** interest on so much of such amount as exceeds the 2-percent portion shall be paid at a rate equal to 45 percent of the annual rate provided by subsection (a).

For purposes of this subsection, the amount of any deficiency which is prorated to installments payable under section 6166 shall be treated as an amount of tax payable in installments under such section.

**§ 6601(j)(2) 2-percent portion.** For purposes of this subsection, the term “2-percent portion” means the lesser of—

**§ 6601(j)(2)(A)**

**§ 6601(j)(2)(A)(i)** the amount of the tentative tax which would be determined under the rate schedule set forth in section 2001(c) if the amount with respect to which such tentative tax is to be computed were the sum of $1,000,000 and the applicable exclusion amount in effect under section 2010(c), reduced by

**§ 6601(j)(2)(A)(ii)** the applicable credit amount in effect under section 2010(c), or

**§ 6601(j)(2)(B)** the amount of the tax imposed by chapter 11 which is extended as provided in section 6166.

**§ 6601(j)(3) Inflation adjustment.** In the case of estates of decedents dying in a calendar year after 1998, the $1,000,000 amount contained in paragraph (2)(A) shall be increased by an amount equal to—

**§ 6601(j)(3)(A)** $1,000,000, multiplied by

**§ 6601(j)(3)(B)** the cost-of-living adjustment determined under section 1(f)(3) for such calendar year by substituting “calendar year 1997” for “calendar year 2016” in subparagraph (A)(ii) thereof.

If any amount as adjusted under the preceding sentence is not a multiple of $10,000, such amount shall be rounded to the next lowest multiple of $10,000.

**§ 6601(j)(4) Treatment of payments.** If the amount of tax imposed by chapter 11 which is extended as provided in section 6166 exceeds the 2-percent portion, any payment of a portion of such amount shall, for purposes of computing interest for periods after such payment, be treated as reducing the 2-percent portion by an amount which bears the same ratio to the amount of such payment as the amount of the 2-percent portion (determined without regard to this paragraph) bears to the amount of the tax which is extended as provided in section 6166.

## § 6601(k) No interest on certain adjustments

For provisions prohibiting interest on certain adjustments in tax, see section 6205(a).

## Regulations

- [Treas. Reg. § 20.6601-1](/26/reg/20.6601-1.md): Interest on underpayment, nonpayment, or extensions of time for payment, of tax. (interprets § 6601)
- [Treas. Reg. § 25.6601-1](/26/reg/25.6601-1.md): Interest on underpayment, nonpayment, or extensions of time for payment, of tax. (interprets § 6601)
- [Treas. Reg. § 53.6601-1](/26/reg/53.6601-1.md): Interest on underpayment, nonpayment, or extensions of time for payment, of tax. (interprets § 6601)
- [Treas. Reg. § 301.6601-1](/26/reg/301.6601-1.md): Interest on underpayments. (interprets § 6601)

## Final rules

- [62 FR 39115](https://www.federalregister.gov/documents/1997/07/22/97-19052/miscellaneous-sections-affected-by-the-taxpayer-bill-of-rights-2-and-the-personal-responsibility-and) (1997): Miscellaneous Sections Affected by the Taxpayer Bill of Rights 2 and the Personal Responsibility and Work Opportunity Reconciliation Act of 1996

## Leading cases

- [In re Resyn Corp., 851 F.2d 660 (3rd Cir. 1988)](https://www.courtlistener.com/opinion/508739/in-the-matter-of-resyn-corporation-appellantcross-appellee-v-united/)
- [Baptiste v. Commissioner, 29 F.3d 1533 (11th Cir. 1994)](https://www.courtlistener.com/opinion/674676/richard-m-baptiste-transferee-v-commissioner-of-internal-revenue/)
- [Northern States Power Co. v. United States, 73 F.3d 764 (8th Cir. 1996)](https://www.courtlistener.com/opinion/710907/northern-states-power-company-a-minnesota-corporation-and-northern-states/)

## Connections

Cites: § 1 Tax imposed; § 531 Imposition of accumulated earnings tax; § 2001 Imposition and rate of tax; § 2010 Unified credit against estate tax; § 3301 Rate of tax; § 6157 Payment of Federal unemployment tax on quarterly or other time period basis; § 6159 Agreements for payment of tax liability in installments; § 6166 Extension of time for payment of estate tax where estate consists largely of interest in closely held business; § 6205 Special rules applicable to certain employment taxes; § 6211 Definition of a deficiency; § 6213 Restrictions applicable to deficiencies; petition to Tax Court; § 6511 Limitations on credit or refund; § 6611 Interest on overpayments; § 6621 Determination of rate of interest; § 6651 Failure to file tax return or to pay tax; § 6654 Failure by individual to pay estimated income tax

Cited by: § 163 Interest; § 860 Deduction for deficiency dividends; § 877A Tax responsibilities of expatriation; § 995 Taxation of DISC income to shareholders; § 1016 Adjustments to basis; § 1260 Gains from constructive ownership transactions; § 1291 Interest on tax deferral; § 1294 Election to extend time for payment of tax on undistributed earnings; § 1363 Effect of election on corporation; § 2053 Expenses, indebtedness, and taxes; § 5684 Penalties relating to the payment and collection of liquor taxes; § 6166 Extension of time for payment of estate tax where estate consists largely of interest in closely held business; § 6167 Extension of time for payment of tax attributable to recovery of foreign expropriation losses; § 6504 Cross references; § 6603 Deposits made to suspend running of interest on potential underpayments, etc.; § 6621 Determination of rate of interest; § 7518 Tax incentives relating to merchant marine capital construction funds

Derived from: 1939 § 56(b); 1939 § 59(d); 1939 § 146; 1939 § 272(i); 1939 § 292; 1939 § 294; 1939 § 295-298; 1939 § 890; 1939 § 891; 1939 § 892; 1939 § 893; 1939 § 925; 1939 § 1020; 1939 § 1021; 1939 § 1022; 1939 § 1023; 1939 § 1420(b); 1939 § 1530(c); 1939 § 1605(b); 1939 § 1605(c); 1939 § 1717; 1939 § 1853(c); 1939 § 2403(b); 1939 § 2451(b); 1939 § 2475; 1939 § 2706; 1939 § 3310(a); 1939 § 3310(b); 1939 § 3310(c); 1939 § 3310(d); 1939 § 3311; 1939 § 3448(b); 1939 § 3470; 1939 § 3495; 1939 § 3655(b); 1939 § 3779(i); 1939 § 3794

## Amendments

- 1954-08-16: [Act Aug. 16, 1954, ch. 736](/26/act/1954-ch736.md), 68A Stat. 817
- 1958-09-02: [Pub. L. 85-866](/26/act/85-866.md), 72 Stat. 1658
- 1961-06-29: [Pub. L. 87-61](/26/act/87-61.md), 75 Stat. 126
- 1962-10-16: [Pub. L. 87-834](/26/act/87-834.md), 76 Stat. 972
- 1964-09-02: [Pub. L. 88-571](/26/act/88-571.md), 78 Stat. 858
- 1966-04-08: [Pub. L. 89-384](/26/act/89-384.md), 80 Stat. 104
- 1967-12-27: [Pub. L. 90-225](/26/act/90-225.md), 81 Stat. 731
- 1969-08-07: [Pub. L. 91-53](/26/act/91-53.md), 83 Stat. 92
- 1969-12-30: [Pub. L. 91-172](/26/act/91-172.md), 83 Stat. 531
- 1971-12-10: [Pub. L. 92-178](/26/act/92-178.md), 85 Stat. 559
- 1974-09-02: [Pub. L. 93-406](/26/act/93-406.md), 88 Stat. 930
- 1975-01-03: [Pub. L. 93-625](/26/act/93-625.md), 88 Stat. 2115
- 1976-10-02: [Pub. L. 94-452](/26/act/94-452.md), 90 Stat. 1514
- 1976-10-04: [Pub. L. 94-455](/26/act/94-455.md), 90 Stat. 1728
- 1977-05-23: [Pub. L. 95-30](/26/act/95-30.md), 91 Stat. 150
- 1978-11-10: [Pub. L. 95-628](/26/act/95-628.md), 92 Stat. 3632
- 1980-04-02: [Pub. L. 96-223](/26/act/96-223.md), 94 Stat. 253
- 1982-09-03: [Pub. L. 97-248](/26/act/97-248.md), 96 Stat. 635
- 1983-08-12: [Pub. L. 98-76](/26/act/98-76.md), 97 Stat. 429
- 1984-07-18: [Pub. L. 98-369](/26/act/98-369.md), 98 Stat. 696
- 1986-10-22: [Pub. L. 99-514](/26/act/99-514.md), 100 Stat. 2714
- 1987-12-22: [Pub. L. 100-203](/26/act/100-203.md), 101 Stat. 1330
- 1988-11-10: [Pub. L. 100-647](/26/act/100-647.md), 102 Stat. 3569
- 1989-12-19: [Pub. L. 101-239](/26/act/101-239.md), 103 Stat. 2400
- 1990-11-05: [Pub. L. 101-508](/26/act/101-508.md), 104 Stat. 1388
- 1996-07-30: [Pub. L. 104-168](/26/act/104-168.md), 110 Stat. 1458
- 1997-08-05: [Pub. L. 105-34](/26/act/105-34.md), 111 Stat. 846
- 1998-07-22: [Pub. L. 105-206](/26/act/105-206.md), 112 Stat. 741
- 2005-12-21: [Pub. L. 109-135](/26/act/109-135.md), 119 Stat. 2635
- 2015-11-02: [Pub. L. 114-74](/26/act/114-74.md), 129 Stat. 638
- 2017-12-22: [Pub. L. 115-97](/26/act/115-97.md), 131 Stat. 2060
- 2018-03-23: [Pub. L. 115-141](/26/act/115-141.md), 132 Stat. 1204