§ 667.
(a)
General rule
The total of the amounts which are treated under section 666 as having been distributed by a trust in a preceding taxable year shall be included in the income of a beneficiary of the trust when paid, credited, or required to be distributed to the extent that such total would have been included in the income of such beneficiary under section 662(a)(2) (and, with respect to any tax-exempt interest to which section 103 applies, under section 662(b)) if such total had been paid to such beneficiary on the last day of such preceding taxable year. The tax imposed by this subtitle on a beneficiary for a taxable year in which any such amount is included in his income shall be determined only as provided in this section and shall consist of the sum of—
(1)
a partial tax computed on the taxable income reduced by an amount equal to the total of such amounts, at the rate and in the manner as if this section had not been enacted,
(2)
a partial tax determined as provided in subsection (b) of this section, and
(3)
in the case of a foreign trust, the interest charge determined as provided in section 668.
(b)
Tax on distribution
(1)
In general
The partial tax imposed by subsection (a)(2) shall be determined.
(A)
by determining the number of preceding taxable years of the trust on the last day of which an amount is deemed under section 666(a) to have been distributed,
(B)
by taking from the 5 taxable years immediately preceding the year of the accumulation distribution the 1 taxable year for which the beneficiary’s taxable income was the highest and the 1 taxable year for which his taxable income was the lowest,
(C)
by adding to the beneficiary’s taxable income for each of the 3 taxable years remaining after the application of subparagraph (B) an amount determined by dividing the amount deemed distributed under section 666 and required to be included in income under subsection (a) by the number of preceding taxable years determined under subparagraph (A), and
(D)
by determining the average increase in tax for the 3 taxable years referred to in subparagraph (C) resulting from the application of such subparagraph.
The partial tax imposed by subsection (a)(2) shall be the excess (if any) of the average increase in tax determined under subparagraph (D), multiplied by the number of preceding taxable years determined under subparagraph (A), over the amount of taxes (other than the amount of taxes described in section 665(d)(2)) deemed distributed to the beneficiary under sections 666(b) and (c).
(2)
Treatment of loss years
(3)
Certain preceding taxable years not taken into account
(4)
Effect of other accumulation distributions
(5)
Multiple distributions in the same taxable year
(6)
Adjustment in partial tax for estate and generation-skipping transfer taxes attributable to partial tax
(A)
In general
The partial tax shall be reduced by an amount which is equal to the pre-death portion of the partial tax multiplied by a fraction—
(i)
the numerator of which is that portion of the tax imposed by chapter 11 or 13, as the case may be, which is attributable (on a proportionate basis) to amounts included in the accumulation distribution, and
(ii)
the denominator of which is the amount of the accumulation distribution which is subject to the tax imposed by chapter 11 or 13, as the case may be.
(B)
Partial tax determined without regard to this paragraph
([Aug. 16, 1954, ch. 736], [68A Stat. 225]; [Pub. L. 91–172, title III, § 331(a)], Dec. 30, 1969, [83 Stat. 594]; [Pub. L. 94–455, title VII, § 701(a)(1)], title X, § 1014(a), Oct. 4, 1976, [90 Stat. 1575], 1617; [Pub. L. 95–30, title I, § 102(b)(8)], May 23, 1977, [91 Stat. 138]; [Pub. L. 95–600, title VII], §§ 701(q)(1)(B), (C), (r)(1), 702(o)(1), Nov. 6, 1978, [92 Stat. 2909], 2910, 2936; [Pub. L. 99–514, title I, § 104(b)(10)], Oct. 22, 1986, [100 Stat. 2105].)