26 USC 6601 - Interest on underpayment, nonpayment, or extensions of time for payment, of tax

U.S Code last checked for updates: Sep 26, 2025

§ 6601.

Interest on underpayment, nonpayment, or extensions of time for payment, of tax

(a)

General rule

(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:

(1)

Extensions of time disregarded

(2)

Jeopardy

(3)

Accumulated earnings tax

(4)

Last date for payment not otherwise prescribed

(c)

Suspension of interest in certain income, estate, gift, and certain excise tax cases

(d)

Income tax reduced by carryback or adjustment for certain unused deductions

(1)

Net operating loss or capital loss carryback

(2)

Foreign tax credit carrybacks

(3)

Certain credit carrybacks

(A)

In general

(B)

Credit carryback defined

(4)

Filing date

(e)

Applicable rules

Except as otherwise provided in this title—

(1)

Interest treated as tax

(2)

Interest on penalties, additional amounts, or additions to the tax

(A)

In general

(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—

(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

(ii)

ends on the date of payment of such addition to tax.

(3)

Payments made within specified period after notice and demand

(f)

Satisfaction by credits

(g)

Limitation on assessment and collection

(h)

Exception as to estimated tax

(i)

Exception as to Federal unemployment tax

(j)

2-percent rate on certain portion of estate tax extended under section 6166

(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)—

(A)

interest on the 2-percent portion of such amount shall be paid at the rate of 2 percent, and

(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.

(2)

2-percent portion

For purposes of this subsection, the term “2-percent portion” means the lesser of—

(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

(ii)

the applicable credit amount in effect under section 2010(c), or

(B)

the amount of the tax imposed by chapter 11 which is extended as provided in section 6166.

(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—

(A)

$1,000,000, multiplied by

(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.

(4)

Treatment of payments

(k)

No interest on certain adjustments

(Aug. 16, 1954, ch. 736, 68A Stat. 817; Pub. L. 85–866, title I, §§ 66(c), 83(a)(1), 84(a), title II, § 206(e), Sept. 2, 1958, 72 Stat. 1658, 1663, 1664, 1685; Pub. L. 87–61, title II, § 203(c)(2), June 29, 1961, 75 Stat. 126; Pub. L. 87–834, § 2(e)(3), Oct. 16, 1962, 76 Stat. 972; Pub. L. 88–571, § 3(d), Sept. 2, 1964, 78 Stat. 858; Pub. L. 89–384, § 1(f), Apr. 8, 1966, 80 Stat. 104; Pub. L. 90–225, § 2(e), Dec. 27, 1967, 81 Stat. 731; Pub. L. 91–53, § 2(e), Aug. 7, 1969, 83 Stat. 92; Pub. L. 91–172, title I, § 101(j)(49), title V, § 512(e)(3), Dec. 30, 1969, 83 Stat. 531, 641;

cite as: 26 USC 6601