2005—Subsec. (b)(2)(C). Pub. L. 109–135 substituted “subparagraph (B)” for “subparagraph (C)”.

2004—Subsec. (a)(1)(B)(i). Pub. L. 108–311, § 207(1), inserted “, determined without regard to subsections (b)(1), (b)(2), and (d)(1)(B) thereof” after “section 152”.

Subsec. (b)(1)(A)(i). Pub. L. 108–311, § 202(a), amended cl. (i) generally. Prior to amendment, cl. (i) read as follows: “a son, stepson, daughter, or stepdaughter of the taxpayer, or a descendant of a son or daughter of the taxpayer, but if such son, stepson, daughter, stepdaughter, or descendant is married at the close of the taxpayer’s taxable year, only if the taxpayer is entitled to a deduction for the taxable year for such person under section 151 (or would be so entitled but for paragraph (2) or (4) of section 152 (e)), or”.

Subsec. (b)(2). Pub. L. 108–311, § 202(b)(1), redesignated subpars. (B) to (D) as (A) to (C), respectively, and struck out former subpar. (A) which read as follows: “a legally adopted child of a person shall be considered a child of such person by blood;”.

Subsec. (b)(3)(B)(i), (ii). Pub. L. 108–311, § 202(b)(2), amended cls. (i) and (ii) generally. Prior to amendment, cls. (i) and (ii) read as follows:

“(i) paragraph (9) of section 152 (a), or

“(ii) subsection (c) of section 152.”

1988—Subsec. (d). Pub. L. 100–647 substituted “the taxes imposed by sections 1 and 55” for “the tax imposed by section 1”.

1986—Subsec. (a)(3)(B). Pub. L. 99–514, § 1708(a)(1), amended subpar. (B) generally. Prior to amendment, subpar. (B) read as follows: “the date which is—

“(i) December 31, 1982, in the case of service in the combat zone designated for purposes of the Vietnam conflict, or

“(ii) 2 years after the date designated under section 112 as the date of termination of combatant activities in that zone, in the case of any combat zone other than that referred to in clause (i).”

Subsec. (c). Pub. L. 99–514, § 1301(j)(10), substituted “section 7703 (b)” for “section 143 (b)”.

1984—Subsec. (b)(1)(A). Pub. L. 98–369, § 423(c)(2)(A), substituted “which constitutes for more than one-half of such taxable year” for “which constitutes for such taxable year”.

Subsec. (b)(1)(A)(i). Pub. L. 98–369, § 423(c)(2)(B), inserted “(or would be so entitled but for paragraph (2) or (4) of section 152 (e))”.

1983—Subsec. (a)(3)(B)(i). Pub. L. 97–448 substituted “December 31, 1982” for “January 2, 1978”.

1976—Subsec. (a)(3)(B). Pub. L. 94–569 substituted “the date which is” for “the date which is 2 years after” in provisions preceding cl. (i), substituted “January 2, 1978” for “the date of the enactment of this paragraph” in cl. (i), and substituted “2 years after the date” for “the date” in cl. (ii).

Subsec. (b)(3)(B)(ii). Pub. L. 94–455, § 1901(b)(9), redesignated cl. (iii) as (ii) and struck out former cl. (ii) which provided that an individual who was a dependent solely by reason of par. (10) of section 152 (a) would not be considered as a head of a household.

Subsec. (c). Pub. L. 94–455, § 1901(a)(1), substituted “shall be treated as not married at the close of the taxable year” for “shall not be considered as married”.

1975—Subsec. (a)(3). Pub. L. 93–597 added par. (3).

1969—Subsec. (a). Pub. L. 91–172 redesignated subsec. (b) as (a). See sec. 1 (a) of this title.

Subsec. (b). Pub. L. 91–172 redesignated provisions of former section 1 (b)(2) to (4) of this title as subsec. (b). Former subsec. (b) redesignated (a), with minor changes.

Subsec. (c). Pub. L. 91–172 added subsec. (c).

Subsec. (d). Pub. L. 91–172 redesignated as subsec. (d) provisions of former section 1 (d) with minor changes.

Subsec. (e). Pub. L. 91–172 redesignated as subsec. (e) provisions of former section 1 (e).

1964—Subsec. (a). Pub. L. 88–272 inserted reference to section 141.

Pub. L. 108–311, title II, § 208, Oct. 4, 2004, 118 Stat. 1178, provided that: “The amendments made by this title [amending this section and sections 21, 24, 25B, 32, 42, 51, 72, 105, 120, 125, 129, 132, 151 to 153, 170, 213, 220, 221, 529, 2032A, 2057, 7701, 7702B, and 7703 of this title] shall apply to taxable years beginning after December 31, 2004.”

Amendment by 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 1301(j)(10) of Pub. L. 99–514 applicable to bonds issued after Aug. 15, 1986, except as otherwise provided, see sections 1311 to 1318 of Pub. L. 99–514, set out as an Effective Date; Transitional Rules note under section 141 of this title.

Section 1708(b) of Pub. L. 99–514 provided that: “The amendments made by this section [amending this section and sections 692, 6013, and 7508 of this title] shall apply to taxable years beginning after December 31, 1982.”

Section 423(d) of Pub. L. 98–369 provided that: “The amendments made by this section [amending this section and sections 43, 44A, 105, 143, 152, and 213 of this title] shall apply to taxable years beginning after December 31, 1984.”

Section 1901(d) of Pub. L. 94–455 provided that: “Except as otherwise expressly provided in this section, the amendments made by this section [see Tables for classification] shall apply with respect to taxable years beginning after December 31, 1976. The amendments made by subsections (a)(29) and (b)(10) shall apply with respect to taxable years ending after the date of the enactment of this Act [Oct. 4, 1976].”

Amendment by Pub. L. 93–597 applicable to taxable years ending on or after Feb. 28, 1961, see section 3(c) of Pub. L. 93–597, set out as a note under section 6013 of this title.

Amendment by Pub. L. 91–172 applicable to taxable years beginning after Dec. 31, 1970, except that subsec. (c) is applicable to taxable years beginning after Dec. 31, 1969, see section 803(f) of Pub. L. 91–172, set out as a note under section 1 of this title.

Amendment by Pub. L. 88–272, except for purposes of section 21 of this title, effective with respect to taxable years beginning after Dec. 31, 1963, see section 131 of Pub. L. 88–272, set out as a note under section 1 of this title.