View all text of Part III [§ 15 - § 15]
§ 15. Effect of changes
(a) General rule
If any rate of tax imposed by this chapter changes, and if the taxable year includes the effective date of the change (unless that date is the first day of the taxable year), then—
(1) tentative taxes shall be computed by applying the rate for the period before the effective date of the change, and the rate for the period on and after such date, to the taxable income for the entire taxable year; and
(2) the tax for such taxable year shall be the sum of that proportion of each tentative tax which the number of days in each period bears to the number of days in the entire taxable year.
(b) Repeal of tax
For purposes of subsection (a)—
(1) if a tax is repealed, the repeal shall be considered a change of rate; and
(2) the rate for the period after the repeal shall be zero.
(c) Effective date of change
For purposes of subsections (a) and (b)—
(1) if the rate changes for taxable years “beginning after” or “ending after” a certain date, the following day shall be considered the effective date of the change; and
(2) if a rate changes for taxable years “beginning on or after” a certain date, that date shall be considered the effective date of the change.
(d) Section not to apply to inflation adjustments
(e) References to highest rate
(f) Rate reductions enacted by Economic Growth and Tax Relief Reconciliation Act of 2001
(Aug. 16, 1954, ch. 736, 68A Stat. 12, § 21; Pub. L. 88–272, title I, § 132, Feb. 26, 1964, 78 Stat. 30; Pub. L. 91–172, title VIII, § 803(e), Dec. 30, 1969, 83 Stat. 685; Pub. L. 92–178, title II, § 205, Dec. 10, 1971, 85 Stat. 511; Pub. L. 94–12, title III, § 305(b)(2), Mar. 29, 1975, 89 Stat. 45; Pub. L. 94–164, § 4(d)(2), Dec. 23, 1975, 89 Stat. 975; Pub. L. 94–455, title IX, § 901(c)(2), Oct. 4, 1976, 90 Stat. 1607; Pub. L. 95–30, title I, § 101(d)(2), May 23, 1977, 91 Stat. 133; Pub. L. 95–600, title I, § 106, Nov. 6, 1978, 92 Stat. 2776; Pub. L. 97–34, title I, § 101(d)(3), Aug. 13, 1981, 95 Stat. 184; renumbered § 15, Pub. L. 98–369, div. A, title IV, § 474(b)(1), July 18, 1984, 98 Stat. 830; Pub. L. 99–514, title I, § 101(b), Oct. 22, 1986, 100 Stat. 2099; Pub. L. 100–647, title I, § 1006(a), Nov. 10, 1988, 102 Stat. 3393; Pub. L. 107–16, title I, § 101(c)(3), June 7, 2001, 115 Stat. 43.)