
From the U.S. Code Online via GPO Access
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[Laws in effect as of January 2, 2001]
[Document not affected by Public Laws enacted between
  January 2, 2001 and January 28, 2002]
[CITE: 26USC6601]

 
                     TITLE 26--INTERNAL REVENUE CODE
 
                Subtitle F--Procedure and Administration
 
                          CHAPTER 67--INTEREST
 
                 Subchapter A--Interest on Underpayments
 
Sec. 6601. Interest on underpayment, nonpayment, or extensions 
        of time for payment, of tax
        

(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.

(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

        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.

                      (2) Installment payments

        In the case of an election under section 6156(a) to pay the tax 
    in installments--
            (A) The date prescribed for payment of each installment of 
        the tax shown on the return shall be determined under section 
        6156(b), and
            (B) The last date prescribed for payment of the first 
        installment shall be deemed the last date prescribed for payment 
        of any portion of the tax not shown on the return.

                            (3) 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.

                    (4) 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.

         (5) 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).

(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. In 
the case of a settlement under section 6224(c) which results in the 
conversion of partnership items to nonpartnership items pursuant to 
section 6231(b)(1)(C), the preceding sentence shall apply to a 
computational adjustment resulting from such settlement in the same 
manner as if such adjustment were a deficiency and such settlement were 
a waiver referred to in the preceding sentence.

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

          (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.

                  (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.

                    (3) Certain credit carrybacks

        (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.

        (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).

                           (4) Filing date

        For purposes of this subsection, the term ``filing date'' has 
    the meaning given to such term by section 6611(f)(3)(A).\1\
---------------------------------------------------------------------------
    \1\ See References in Text note below.
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(e) Applicable rules

    Except as otherwise provided in this title--

                     (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.

    (2) Interest on penalties, additional amounts, or additions 
                                 to the tax

        (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.

        (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

        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.

(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.

(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.

(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.

(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.

(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 1992'' in subparagraph (B) 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

        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.

(k) No interest on certain adjustments

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

(Aug. 16, 1954, ch. 736, 68A Stat. 817; Pub. L. 85-866, title I, 
Secs. 66(c), 83(a)(1), 84(a), title II, Sec. 206(e), Sept. 2, 1958, 72 
Stat. 1658, 1663, 1664, 1685; Pub. L. 87-61, title II, Sec. 203(c)(2), 
June 29, 1961, 75 Stat. 126; Pub. L. 87-834, Sec. 2(e)(3), Oct. 16, 
1962, 76 Stat. 972; Pub. L. 88-571, Sec. 3(d), Sept. 2, 1964, 78 Stat. 
858; Pub. L. 89-384, Sec. 1(f), Apr. 8, 1966, 80 Stat. 104; Pub. L. 90-
225, Sec. 2(e), Dec. 27, 1967, 81 Stat. 731; Pub. L. 91-53, Sec. 2(e), 
Aug. 7, 1969, 83 Stat. 92; Pub. L. 91-172, title I, Sec. 101(j)(49), 
title V, Sec. 512(e)(3), Dec. 30, 1969, 83 Stat. 531, 641; Pub. L. 92-
178, title VI, Sec. 601(d)(3), Dec. 10, 1971, 85 Stat. 559; Pub. L. 93-
406, title II, Sec. 1016(a)(17), Sept. 2, 1974, 88 Stat. 930; Pub. L. 
93-625, Sec. 7(a)(2)(A), (b)(1), Jan. 3, 1975, 88 Stat. 2115; Pub. L. 
94-452, Sec. 3(c)(3), Oct. 2, 1976, 90 Stat. 1514; Pub. L. 94-455, title 
XIII, Sec. 1307(d)(2)(H), title XVI, Sec. 1605(b)(10), title XIX, 
Secs. 1906(a)(34), (b)(13)(A), title XX, Sec. 2004(b), title XXI, 
Sec. 2107(g)(2)(C), Oct. 4, 1976, 90 Stat. 1728, 1755, 1829, 1834, 1867, 
1904; Pub. L. 95-30, title II, Sec. 202(d)(4)(C), May 23, 1977, 91 Stat. 
150; Pub. L. 95-628, Sec. 8(c)(2), Nov. 10, 1978, 92 Stat. 3632; Pub. L. 
96-223, title I, Sec. 101(f)(7), Apr. 2, 1980, 94 Stat. 253; Pub. L. 97-
248, title III, Secs. 344(b)(1), 346(c)(2), Sept. 3, 1982, 96 Stat. 635, 
637; Pub. L. 98-76, title II, Sec. 231(b)(2)(D), Aug. 12, 1983, 97 Stat. 
429; Pub. L. 98-369, div. A, title I, Sec. 158(a), title II, 
Sec. 211(b)(26), title IV, Sec. 412(b)(7), title VII, Sec. 714(n)(1), 
July 18, 1984, 98 Stat. 696, 757, 792, 963; Pub. L. 99-514, title XIV, 
Sec. 1404(c)(3), title XV, Secs. 1511(c)(11), 1512(a), 1564(a), Oct. 22, 
1986, 100 Stat. 2714, 2745, 2746, 2762; Pub. L. 100-203, title X, 
Sec. 10301(b)(5), Dec. 22, 1987, 101 Stat. 1330-429; Pub. L. 100-647, 
title I, Secs. 1015(b)(2)(C), 1018(u)(42), title VI, Sec. 6234(b)(1), 
title VII, Sec. 7106(c)(5), Nov. 10, 1988, 102 Stat. 3569, 3592, 3736, 
3774; Pub. L. 101-239, title VII, Sec. 7721(c)(8), Dec. 19, 1989, 103 
Stat. 2400; Pub. L. 101-508, title XI, Sec. 11801(c)(20)(B), Nov. 5, 
1990, 104 Stat. 1388-528; Pub. L. 104-168, title III, Sec. 303(a), 
(b)(1), July 30, 1996, 110 Stat. 1458; Pub. L. 105-34, title V, 
Secs. 501(e), 503(a), (c)(2), (3), title X, Sec. 1055(a), title XII, 
Sec. 1242(a), Aug. 5, 1997, 111 Stat. 846, 852, 853, 944, 1029; Pub. L. 
105-206, title III, Sec. 3301(b), July 22, 1998, 112 Stat. 741.)

  Adjustment of Dollar Amount Used in Determining ``2-Percent Portion''

        For adjustment of dollar amount used in determining ``2-percent 
    portion'' for purpose of calculating interest under subsec. (j) of 
    this section in the case of decedents dying in calendar year 2001, 
    see section 3.25 of Revenue Procedure 2001-13, set out as a note 
    under section 1 of this title.

                       References in Text

    Section 6611(f)(3)(A), referred to in subsec. (d)(4), was 
redesignated section 6611(f)(4)(A) of this title by Pub. L. 105-34, 
title X, Sec. 1055(b)(1), Aug. 5, 1997, 111 Stat. 944.


                               Amendments

    1998--Subsec. (f). Pub. L. 105-206 inserted at end ``The preceding 
sentence shall not apply to the extent that section 6621(d) applies.''
    1997--Subsec. (c). Pub. L. 105-34, Sec. 1242(a), inserted at end 
``In the case of a settlement under section 6224(c) which results in the 
conversion of partnership items to nonpartnership items pursuant to 
section 6231(b)(1)(C), the preceding sentence shall apply to a 
computational adjustment resulting from such settlement in the same 
manner as if such adjustment were a deficiency and such settlement were 
a waiver referred to in the preceding sentence.''
    Subsec. (d)(2) to (4). Pub. L. 105-34, Sec. 1055(a), added par. (2) 
and redesignated former pars. (2) and (3) as (3) and (4), respectively.
    Subsec. (j). Pub. L. 105-34, Sec. 503(c)(3), substituted ``2-
percent'' for ``4-percent'' in heading.
    Subsec. (j)(1). Pub. L. 105-34, Sec. 503(a), reenacted par. heading 
without change and amended text generally. Prior to amendment, text read 
as follows: ``If the time for payment of an amount of tax imposed by 
chapter 11 is extended as provided in section 6166, interest on the 4-
percent portion of such amount shall (in lieu of the annual rate 
provided by subsection (a)) be paid at the rate of 4 percent. 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.''
    Subsec. (j)(2). Pub. L. 105-34, Sec. 503(a), amended heading and 
text generally. Prior to amendment, text read as follows: ``For purposes 
of this subsection, the term `4-percent portion' means the lesser of--
        ``(A) $345,800 reduced by the amount of the credit allowable 
    under section 2010(a); or
        ``(B) the amount of the tax imposed by chapter 11 which is 
    extended as provided in section 6166.''
    Subsec. (j)(3). Pub. L. 105-34, Sec. 501(e), added par. (3). Former 
par. (3) redesignated (4).
    Subsec. (j)(4). Pub. L. 105-34, Sec. 503(c)(2), substituted ``2-
percent'' for ``4-percent'' wherever appearing.
    Pub. L. 105-34, Sec. 501(e), redesignated par. (3) as (4).
    1996--Subsec. (e)(2)(A). Pub. L. 104-168, Sec. 303(b)(1), 
substituted ``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)'' for ``10 days from the date 
of notice and demand therefor''.
    Subsec. (e)(3). Pub. L. 104-168, Sec. 303(a), substituted 
``specified period'' for ``10 days'' in heading and amended text 
generally. Prior to amendment, text read as follows: ``If notice and 
demand is made for payment of any amount, and if such amount is paid 
within 10 days 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.''
    1990--Subsec. (b)(2). Pub. L. 101-508 struck out ``or 6158(a)'' 
after ``6156(a)'' in introductory provisions, struck out ``or 6158(a), 
as the case may be'' after ``6156(a)'' in subpar. (A), and struck out at 
end ``For purposes of subparagraph (A), section 6158(a) shall be treated 
as providing that the date prescribed for payment of each installment 
shall not be later than the date prescribed for payment of the 1985 
installment.''
    1989--Subsec. (e)(2). Pub. L. 101-239 substituted ``section 
6651(a)(1) or 6653 or under part II of subchapter A of chapter 68'' for 
``section 6651(a)(1), 6653, 6659, 6660, or 6661'' in subpars. (A) and 
(B).
    1988--Subsec. (b)(1). Pub. L. 100-647, Sec. 6234(b)(1), inserted 
``or any installment agreement entered into under section 6159'' after 
``time for payment''.
    Subsec. (b)(2). Pub. L. 100-647, Sec. 1018(u)(42), made technical 
correction to directory language of Pub. L. 99-514, Sec. 1404(c)(3), see 
1986 Amendment note below.
    Subsec. (e)(2)(A), (B). Pub. L. 100-647, Sec. 1015(b)(2)(C), 
substituted ``6653, 6659'' for ``6659''.
    Subsec. (i). Pub. L. 100-647, Sec. 7106(c)(5), struck out ``or 
3321'' after ``3301''.
    1987--Subsec. (h). Pub. L. 100-203 substituted ``section 6654 or 
6655'' for ``section 6154 or 6654''.
    1986--Subsec. (a). Pub. L. 99-514, Sec. 1511(c)(11), substituted 
``the underpayment rate established under section 6621'' for ``an annual 
rate established under section 6621''.
    Subsec. (b)(2). Pub. L. 99-514, Sec. 1404(c)(3), as amended by Pub. 
L. 100-647, Sec. 1018(u)(42), substituted ``6156(a) or 6158(a)'' for 
``6152(a), 6156(a), or 6158(a)'' in introductory provisions and 
``6156(b) or 6158(a)'' for ``6152(b), 6156(b), or 6158(a)'' in subpar. 
(A).
    Subsec. (b)(4), (5). Pub. L. 99-514, Sec. 1512(a), added par. (4) 
and redesignated former par. (4) as (5).
    Subsec. (c). Pub. L. 99-514, Sec. 1564(a), inserted ``and interest 
shall not be imposed during such period on any interest with respect to 
such deficiency for any prior period''.
    1984--Subsec. (d)(2)(A). Pub. L. 98-369, Sec. 714(n)(1), made 
technical correction to directory language of Pub. L. 97-248, 
Sec. 346(c)(2)(B). See 1982 Amendment note below.
    Subsec. (d)(3), (4). Pub. L. 98-369, Sec. 211(b)(26), redesignated 
par. (4) as (3) and struck out former par. (3) which had provided that 
if the amount of any tax imposed by subtitle A was reduced by operation 
of section 815(d)(5) (relating to reduction of policyholders surplus 
account of life insurance companies for certain unused deductions), such 
reduction in tax would not affect the computation of interest under this 
section for the period ending with the last day of the last taxable year 
to which the loss described in section 815(d)(5)(A) was carried under 
section 812(b)(2).
    Subsec. (e)(2). Pub. L. 98-369, Sec. 158(a), in amending par. (2) 
generally, inserted ``(other than an addition to tax imposed under 
section 6651(a)(1), 6659, 6660, or 6661)'', and added subpar. (B).
    Subsec. (h). Pub. L. 98-369, Sec. 412(b)(7), amended subsec. (h) 
generally, substituting ``any estimated tax required to be paid by 
section 6154 or 6654'' for ``estimated tax required by section 6153 or 
section 6154''.
    1983--Subsec. (i). Pub. L. 98-76 inserted ``or 3321'' after 
``3301''.
    1982--Subsec. (d)(1). Pub. L. 97-248, Sec. 346(c)(2)(A), substituted 
``the filing date for the taxable year'' for ``the last day of the 
taxable year''.
    Subsec. (d)(2)(A). Pub. L. 97-248, Sec. 346(c)(2)(B), as amended by 
Pub. L. 98-369, Sec. 346(c)(2)(B), substituted ``the filing date for'' 
for ``the last day of'' in two places.
    Subsec. (d)(4). Pub. L. 97-248, Sec. 346(c)(2)(C), added par. (4).
    Subsec. (e). Pub. L. 97-248, Sec. 344(b)(1), struck out par. (2) 
which had provided that no interest under this section was to be imposed 
on the interest provided by this section, and redesignated pars. (3) and 
(4) as (2) and (3), respectively.
    1980--Subsec. (c). Pub. L. 96-223 substituted ``certain excise tax 
cases'' for ``chapter 41, 42, 43, or 44 tax cases'' in heading.
    1978--Subsec. (d)(2). Pub. L. 95-628, Sec. 8(c)(2)(A), substituted 
in heading ``Certain credit carrybacks'' for ``Investment credit 
carryback'', designated existing provision as subpar. (A), and in 
subpar. (A) as so designated, inserted heading ``In general'' and in 
text extended the application of the provision to credit carrybacks, 
previously limited to investment credit carrybacks, included other 
credit carrybacks, and added subpar. (B).
    Subsec. (d)(4), (5). Pub. L. 95-628, Sec. 8(c)(2)(B), struck out 
pars. (4) and (5) which provided for work incentive program credit 
carrybacks and new employee credit carrybacks, respectively.
    1977--Subsec. (d)(5). Pub. L. 95-30 added par. (5).
    1976--Subsec. (b)(2). Pub. L. 94-452 substituted ``, 6156(a), or 
6158(a)'' for ``or 6156(a)'' and ``, 6156(b), or 6158(a)'' for ``or 
6156(b)'' and inserted requirement that for purposes of subparagraph 
(A), section 6158(a) of this title shall be treated as providing that 
the date prescribed for payment of each installment shall not be later 
than the date prescribed for payment of the 1985 installment.
    Subsec. (b)(4). Pub. L. 94-455, Sec. 1906(b)(13)(A), struck out ``or 
his delegate'' after ``Secretary''.
    Subsec. (c). Pub. L. 94-455, Secs. 1307(d)(2)(H), 1605(b)(10), 
substituted in heading ``chapter 41, 42'' for ``chapter 42'' and ``43, 
or 44'' for ``or 43''.
    Subsec. (d)(4). Pub. L. 94-455, Sec. 2107(g)(2)(C), inserted ``, an 
investment credit carryback,'' after ``net operating loss carryback''.
    Subsec. (h). Pub. L. 94-455, Sec. 1906(a)(34), struck out ``(or 
section 59 of the Internal Revenue Code of 1939)''.
    Subsecs. (j), (k). Pub. L. 94-455, Sec. 2004(b), added subsec. (j) 
and redesignated former subsec. (j) as (k).
    1975--Subsec. (a). Pub. L. 93-625, Sec. 7(a)(2)(A), substituted ``an 
annual rate established under section 6621'' for ``the rate of 6 percent 
per annum''.
    Subsecs. (b) to (l). Pub. L. 93-625, Sec. 7(b)(1), struck out 
subsec. (b) relating to extensions of time for payment of estate tax, 
redesignated subsecs. (c) to (i) as (b) to (h), respectively, struck out 
subsec. (j) relating to extensions of time for payment of tax 
attributable to recoveries of foreign expropriation losses, and 
redesignated subsecs. (k) and (l) as (i) and (j), respectively.
    1974--Subsec. (d). Pub. L. 93-406 inserted reference to chapter 43 
in heading, and substituted ``certain excise'' for ``chapter 42'' in 
text.
    1971--Subsec. (e)(4). Pub. L. 92-178 added par. (4).
    1969--Subsec. (d). Pub. L. 91-172, Sec. 101(j)(49), inserted 
reference to chapter 42 both in subsec. heading and in text.
    Subsec. (e)(1). Pub. L. 91-172, Sec. 512(e)(3)(A), (B), substituted 
``loss or capital loss carryback'' for ``loss carryback'' in heading, 
and ``net operating loss or net capital loss'' for ``net operating 
loss'' wherever it appears in text.
    Subsec. (e)(2). Pub. L. 91-172, Sec. 512(e)(3)(C), substituted 
``loss carryback or a capital loss carryback'' for ``loss carryback''.
    Subsecs. (k), (l). Pub. L. 91-53 added subsec. (k) and redesignated 
former subsec. (k) as (l).
    1967--Subsec. (e)(2). Pub. L. 90-225 inserted ``, or with respect to 
any portion of an investment credit carryback from a taxable year 
attributable to a net operating 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 last day of such subsequent 
taxable year,'' after ``the investment credit carryback arises''.
    1966--Subsecs. (j), (k). Pub. L. 89-384 added subsec. (j) and 
redesignated former subsec. (j) as (k).
    1964--Subsec. (e). Pub. L. 88-571 added par. (3) and inserted ``or 
adjustment for certain unused deductions'' in heading.
    1962--Subsec. (e). Pub. L. 87-834 designated existing provisions as 
par. (1) and added par. (2).
    1961--Subsec. (c)(2). Pub. L. 87-61 substituted ``6152(a) or 
6156(a)'' for ``6152(a)'' in introductory provisions, and ``6152(b) or 
6156(b), as the case may be'' for ``6152(b)'' in subpar. (A).
    1958--Subsec. (b). Pub. L. 85-866, Secs. 66(c), 206(e), inserted 
reference to section 6166, and substituted ``if the time for payment of 
an amount of such tax is postponed or extended as provided by section 
6163'' for ``if postponement of the payment of an amount of such tax is 
permitted by section 6163(a)''.
    Subsecs. (g) to (j). Pub. L. 85-866, Secs. 83(a)(1), 84(a), added 
subsecs. (g) and (h) and redesignated former subsecs. (g) and (h) as (h) 
and (i), respectively.


                    Effective Date of 1998 Amendment

    Pub. L. 105-206, title III, Sec. 3301(c), July 22, 1998, 112 Stat. 
741, as amended by Pub. L. 105-277, div. J, title IV, Sec. 4002(d), Oct. 
21, 1998, 112 Stat. 2681-906, provided that:
    ``(1) In general.--Except as provided under paragraph (2), the 
amendments made by this section [amending this section and section 6621 
of this title] shall apply to interest for periods beginning after the 
date of the enactment of this Act [July 22, 1998].
    ``(2) Special rule.--Subject to any applicable statute of limitation 
not having expired with regard to either a tax underpayment or a tax 
overpayment, the amendments made by this section shall apply to interest 
for periods beginning before the date of the enactment of this Act if 
the taxpayer--
        ``(A) reasonably identifies and establishes periods of such tax 
    overpayments and underpayments for which the zero rate applies; and
        ``(B) not later than December 31, 1999, requests the Secretary 
    of the Treasury to apply section 6621(d) of the Internal Revenue 
    Code of 1986, as added by subsection (a), to such periods.''


                    Effective Date of 1997 Amendment

    Amendment by section 501(e) of Pub. L. 105-34 applicable to estates 
of decedents dying, and gifts made, after Dec. 31, 1997, see section 
501(f) of Pub. L. 105-34, set out as a note under section 2001 of this 
title.
    Amendment by section 503(a), (c)(2), (3) of Pub. L. 105-34 
applicable to estates of decedents dying after Dec. 31, 1997, with 
special rule in case of estate of any decedent dying before Jan. 1, 
1998, with respect to which there is an election under section 6166 of 
this title, see section 503(d) of Pub. L. 105-34, set out as a note 
under section 163 of this title.
    Section 1055(c) of Pub. L. 105-34 provided that: ``The amendments 
made by this section [amending this section and section 6611 of this 
title] shall apply to foreign tax credit carrybacks arising in taxable 
years beginning after the date of the enactment of this Act [Aug. 5, 
1997].''
    Section 1242(b) of Pub. L. 105-34 provided that: ``The amendment 
made by this section [amending this section] shall apply to adjustments 
with respect to partnership taxable years beginning after the date of 
the enactment of this Act [Aug. 5, 1997].''


                    Effective Date of 1996 Amendment

    Section 303(c) of Pub. L. 104-168 provided that: ``The amendments 
made by this section [amending this section and section 6651 of this 
title] shall apply in the case of any notice and demand given after 
December 31, 1996.''


                    Effective Date of 1989 Amendment

    Amendment by Pub. L. 101-239 applicable to returns the due date for 
which (determined without regard to extensions) is after Dec. 31, 1989, 
see section 7721(d) of Pub. L. 101-239, set out as a note under section 
461 of this title.


                    Effective Date of 1988 Amendment

    Amendment by section 1015(b)(2)(C) of Pub. L. 100-647 applicable to 
returns the due date for which (determined without regard to extensions) 
is after Dec. 31, 1988, see section 1015(b)(4) of Pub. L. 100-647, set 
out as a note under section 6013 of this title.
    Amendment by section 1018(u)(42) of Pub. L. 100-647 effective, 
except as otherwise provided, as if included in the provision of the Tax 
Reform Act of 1986, Pub. L. 99-514, to which such amendment relates, see 
section 1019(a) of Pub. L. 100-647, set out as a note under section 1 of 
this title.
    Amendment by section 6234(b)(1) of Pub. L. 100-647 applicable to 
agreements entered into after Nov. 10, 1988, see section 6234(c) of Pub. 
L. 100-647, set out as an Effective Date note under section 6159 of this 
title.
    Amendment by section 7106(c)(5) of Pub. L. 100-647 applicable to 
remuneration paid after Dec. 31, 1988, see section 7106(d) of Pub. L. 
100-647, set out as a note under section 3321 of this title.


                    Effective Date of 1987 Amendment

    Amendment by Pub. L. 100-203 applicable to taxable years beginning 
after Dec. 31, 1987, see section 10301(c) of Pub. L. 100-203, set out as 
a note under section 585 of this title.


                    Effective Date of 1986 Amendment

    Amendment by section 1404(c)(3) of Pub. L. 99-514 applicable to 
taxable years beginning after Dec. 31, 1986, see section 1404(d) of Pub. 
L. 99-514, set out as a note under section 643 of this title.
    Amendment by section 1511(c)(11) of Pub. L. 99-514 applicable for 
purposes of determining interest for periods after Dec. 31, 1986, see 
section 1511(d) of Pub. L. 99-514, set out as a note under section 47 of 
this title.
    Section 1512(b) of Pub. L. 99-514 provided that: ``The amendments 
made by this section [amending this section] shall apply to returns the 
due date for which (determined without regard to extensions) is after 
December 31, 1985.''
    Section 1564(b) of Pub. L. 99-514 provided that:
    ``(1) Effective date.--The amendment made by subsection (a) 
[amending this section] shall apply to interest accruing after December 
31, 1982.
    ``(2) Statute of limitations.--If refund or credit of any amount 
resulting from the application of the amendment made by subsection (a) 
is prevented at any time before the close of the date which is 1 year 
after the date of the enactment of this Act [Oct. 22, 1986] by the 
operation of any law or rule of law (including res judicata), refund or 
credit of such amount (to the extent attributable to the application of 
the amendment made by subsection (a)) may, nevertheless, be made or 
allowed if claim therefore [sic] is filed before the close of such 1-
year period.''


                    Effective Date of 1984 Amendment

    Section 158(b) of Pub. L. 98-369 provided that: ``The amendment made 
by this section [amending this section] shall apply to interest accrued 
after the date of the enactment of this Act [July 18, 1984], except with 
respect to additions to tax for which notice and demand is made before 
such date.''
    Amendment by section 211(b)(26) of Pub. L. 98-369 applicable to 
taxable years beginning after Dec. 31, 1983, see section 215 of Pub. L. 
98-369, set out as an Effective Date note under section 801 of this 
title.
    Amendment by section 412(b)(7) of Pub. L. 98-369 applicable with 
respect to taxable years beginning after Dec. 31, 1984, see section 
414(a)(1) of Pub. L. 98-369, set out as a note under section 6654 of 
this title.
    Amendment by section 714(n)(1) of Pub. L. 98-369 effective as if 
included in the provision of the Tax Equity and Fiscal Responsibility 
Act of 1982, Pub. L. 97-248, to which such amendment relates, see 
section 715 of Pub. L. 98-369, set out as a note under section 31 of 
this title.


                    Effective Date of 1983 Amendment

    Amendment by Pub. L. 98-76 applicable to remuneration paid after 
June 30, 1986, see section 231(d) of Pub. L. 98-76, set out as an 
Effective Date note under section 3321 of this title.


                    Effective Date of 1982 Amendment

    Amendment by section 344(b)(1) of Pub. L. 97-248 applicable to 
interest accruing after Dec. 31, 1982, see section 344(c) of Pub. L. 97-
248, set out as an Effective Date note under section 6622 of this title.
    Amendment by section 346(c)(2) of Pub. L. 97-248 applicable to 
interest accruing after the 30th day after Sept. 3, 1982, see section 
346(d)(2) of Pub. L. 97-248, set out as a note under section 6611 of 
this title.


                    Effective Date of 1980 Amendment

    Amendment by Pub. L. 96-223 applicable to periods after Feb. 29, 
1980, see section 101(i) of Pub. L. 96-223, set out as a note under 
section 6161 of this title.


                    Effective Date of 1978 Amendment

    Amendment by Pub. L. 95-628 applicable to carrybacks arising in 
taxable years beginning after Nov. 10, 1978, see section 8(d) of Pub. L. 
95-628, set out as a note under section 6511 of this title.


                    Effective Date of 1977 Amendment

    Amendment by Pub. L. 95-30 applicable to taxable years beginning 
after Dec. 31, 1976, and to credit carrybacks from such years, see 
section 202(e) of Pub. L. 95-30, set out as an Effective Date note under 
section 51 of this title.


                    Effective Date of 1976 Amendments

    Amendment by section 2004(b) of Pub. L. 94-455 applicable to estates 
of decedents dying after Dec. 31, 1976, see section 2004(g) of Pub. L. 
94-455, set out as a note under section 6166 of this title.
    Amendment by Pub. L. 94-452 effective Oct. 1, 1977, see section 3(e) 
of Pub. L. 94-452, set out as a note under section 6151 of this title.


                    Effective Date of 1975 Amendment

    Amendment by Pub. L. 93-625 effective July 1, 1975, and applicable 
to amounts outstanding on such date or arising thereafter, see section 
7(e) of Pub. L. 93-625, set out as an Effective Date note under section 
6621 of this title.


                    Effective Date of 1974 Amendment

    Amendment by Pub. L. 93-406 applicable, except as otherwise provided 
in section 1017(c) through (i) of Pub. L. 93-406, for plan years 
beginning after Sept. 2, 1974, but, in the case of plans in existence on 
Jan. 1, 1974, amendment by Pub. L. 93-406 applicable for plan years 
beginning after Dec. 31, 1975, see section 1017 of Pub. L. 93-406, set 
out as an Effective Date; Transitional Rules note under section 410 of 
this title.


                    Effective Date of 1971 Amendment

    Amendment by Pub. L. 92-178 applicable to taxable years beginning 
after Dec. 31, 1971, see section 601(f) of Pub. L. 92-178, set out as a 
note under section 381 of this title.


                    Effective Date of 1969 Amendment

    Amendment by section 101(j)(49) of Pub. L. 91-172 effective Jan. 1, 
1970, see section 101(k)(1) of Pub. L. 91-172, set out as an Effective 
Date note under section 4940 of this title.
    Amendment by section 512(e)(3) of Pub. L. 91-172 applicable with 
respect to net capital losses sustained in taxable years beginning after 
Dec. 31, 1969, see section 512(g) of Pub. L. 91-172, set out as an 
Effective Date of 1969 Amendment note under section 1212 of this title. 
Amendment by Pub. L. 91-53 applicable with respect to calendar years 
beginning after Dec. 31, 1969, see section 4(a) of Pub. L. 91-53, set 
out as an Effective Date note under section 6157 of this title.


                    Effective Date of 1967 Amendment

    Amendment by Pub. L. 90-225 applicable with respect to investment 
credit carrybacks attributable to net operating loss carrybacks from 
taxable years ending after July 31, 1967, see section 2(g) of Pub. L. 
90-225, set out as a note under section 46 of this title.


                    Effective Date of 1966 Amendment

    Amendment by Pub. L. 89-384 applicable with respect to amounts 
received after December 31, 1964, in respect of foreign expropriation 
losses (as defined in section 1351(b) of this title) sustained after 
December 31, 1958, see section 2 of Pub. L. 89-384, set out as an 
Effective Date note under section 1351 of this title.


                    Effective Date of 1964 Amendment

    Amendment by Pub. L. 88-571 effective, with respect to amounts added 
to policyholders surplus accounts, for taxable years beginning after 
Dec. 31, 1958, see section 3(f) of Pub. L. 88-571, set out as a note 
under section 815 of this title.


                    Effective Date of 1962 Amendment

    Amendment by Pub. L. 87-834 applicable with respect to taxable years 
ending after Dec. 31, 1961, see section 2(h) of Pub. L. 87-834, set out 
as an Effective Date note under section 46 of this title.


                    Effective Date of 1961 Amendment

    Amendment by Pub. L. 87-61 effective July 1, 1961, see section 208 
of Pub. L. 87-61, set out as a note under section 4041 of this title.


                    Effective Date of 1958 Amendment

    Amendment by sections 66(c) and 84(a) of Pub. L. 85-866 effective 
Aug. 17, 1954, see section 1(c)(2) of Pub. L. 85-866, set out as a note 
under section 165 of this title.
    Section 83(d) of Pub. L. 85-866 provided that: ``The amendments made 
by subsections (a) [amending this section and section 3794 of I.R.C. 
1939], (b) [amending section 6611 of this title and section 3771 of 
I.R.C. 1939], and (c) [amending section 6611 of this title] shall apply 
only in respect of overpayments credited after December 31, 1957.''
    For effective date of amendment by section 206(e) of Pub. L. 85-866, 
see section 206(f) of Pub. L. 85-866, set out as a note under section 
6161 of this title.


                            Savings Provision

    For provisions that nothing in amendment by Pub. L. 101-508 be 
construed to affect treatment of certain transactions occurring, 
property acquired, or items of income, loss, deduction, or credit taken 
into account prior to Nov. 5, 1990, for purposes of determining 
liability for tax for periods ending after Nov. 5, 1990, see section 
11821(b) of Pub. L. 101-508, set out as a note under section 29 of this 
title.


                Administration of Penalties and Interest

    Pub. L. 105-206, title III, Sec. 3801, July 22, 1998, 112 Stat. 782, 
provided that: ``The Joint Committee on Taxation and the Secretary of 
the Treasury shall each conduct a separate study--
        ``(1) reviewing the administration and implementation by the 
    Internal Revenue Service of the interest and penalty provisions of 
    the Internal Revenue Code of 1986 (including the penalty reform 
    provisions of the Omnibus Budget Reconciliation Act of 1989 [Pub. L. 
    101-239, see Tables for classification]); and
        ``(2) making any legislative and administrative recommendations 
    the Committee or the Secretary deems appropriate to simplify penalty 
    or interest administration and reduce taxpayer burden.
Such studies shall be submitted to the Committee on Ways and Means of 
the House of Representatives and the Committee on Finance of the Senate 
not later than 1 year after the date of the enactment of this Act [July 
22, 1998].''


Interest Not Payable on Underpayments Created or Increased by Tax Reform 
                               Act of 1976

    Section 305 of Pub. L. 95-30, as amended by Pub. L. 99-514, Sec. 2, 
Oct. 22, 1986, 100 Stat. 2095, provided that: ``No interest shall be 
payable for any period before April 16, 1977 (March 16, 1977, in the 
case of a corporation), on any underpayment of a tax imposed by the 
Internal Revenue Code of 1986 [formerly I.R.C. 1954], to the extent that 
such underpayment was created or increased by any provision of the Tax 
Reform Act of 1976 [Pub. L. 94-455].''


                        Interest on Underpayment

    Section 946(a) of Pub. L. 91-172 provided that in the case of any 
taxable year ending before Dec. 30, 1969, no interest on underpayment of 
taxes, to the extent that such underpayment was attributable to the 
amendments made by Pub. L. 91-172, was not to be assessed or collected 
for any period before the 90th day after Dec. 30, 1969.


   Interest Attributable to Net Operating Loss Carryback for Certain 
                      Taxable Years Ending in 1954

    Section 83(e) of Pub. L. 85-866 provided that if by reason of the 
enactment of section 172(b)(1)(A) of this title, a deficiency resulted 
for the first taxable year preceding a taxable year ending after Dec. 
31, 1953 but before Aug. 17, 1954 and an overpayment resulted in the 
second preceding taxable year, then no interest was payable for any 
portion of such deficiency for any period during which there existed a 
corresponding overpayment to which interest was not payable.

                  Section Referred to in Other Sections

    This section is referred to in sections 163, 815, 860, 936, 995, 
1016, 1260, 1291, 1363, 2053, 5684, 6166, 6167, 6404, 6504, 6621, 7404, 
7518 of this title; title 29 section 1307; title 46 App. section 1177.
