1976—Subsec. (a). Pub. L. 94–455, §§ 1901(a)(159), 1906(b)(13)(A), struck out “beginning after December 31, 1953, and ending after the date of enactment of this title” after “group filed for a taxable year”, and “or his delegate” after “Secretary” in two places.

1964—Subsec. (a)(3). Pub. L. 88–272 struck out “(determined without regard to the 2 percent increase provided by section 1503(a))”, before “based on their contributions”.

Amendment by section 1901(a)(159) of Pub. L. 94–455 applicable with respect to taxable years beginning after Dec. 31, 1976, see section 1901(d) of Pub. L. 94–455, set out as a note under section 2 of this title.

Amendment by Pub. L. 88–272 applicable to taxable years beginning after Dec. 31, 1963, see section 234(c) of Pub. L. 88–272, set out as a note under section 1503 of this title.