(a) In general. The partial tax imposed on the beneficiary by section 668(a)(2) shall be the lesser of:

(1) The tax computed under paragraph (b) of this section (the “exact” method), or

(2) The tax computed under paragraph (c) of this section (the “short-cut” method),

except as provided in §1.668(b)-4A (relating to failure to furnish proper information) and paragraph (d) of this section (relating to disallowance of short-cut method). For purposes of this paragraph, the method used in the return shall be accepted as the method that produces the lesser tax. The beneficiary's choice of the two methods is not dependent upon the method that he uses to compute his partial tax imposed by section 668(a)(3).

(b) Computation of partial tax by the exact method. The partial tax referred to in paragraph (a)(1) of this section is computed as follows:

(1) First, compute the tax attributable to the section 666 amounts for each of the preceding taxable years. For purposes of this paragraph, the “section 666 amounts” for a preceding taxable year are the amounts deemed distributed under section 666(a) on the last day of the preceding taxable year, plus the amount of taxes deemed distributed on such day under section 666 (b) or (c). The tax attributable to such amounts in each prior taxable year of the beneficiary is the difference between the tax for such year computed with the inclusion of the section 666 amounts in the beneficiary's gross income and the tax for such year computed without including them in such gross income. Tax computations for each such year shall reflect a taxpayer's marital, dependency, exemption, and filing status for such year. To the extent the undistributed net income of a trust deemed distributed in an accumulation distribution includes amounts received as an accumulation distribution from another trust, for purposes of this paragraph they shall be considered as amounts deemed distributed by the trust under section 666(a) on the last day of each of the preceding taxable years in which such amounts were accumulated by such other trust. For example, assume trust Z, a calendar year trust, received in its taxable year 1975 an accumulation distribution from trust Y, a calendar year trust, that included undistributed net income and taxes of trust Y for the taxable years 1972, 1973, and 1974. To the extent an accumulation distribution made by trust Z in its taxable year 1976 includes such undistributed net income and taxes, it shall be considered an accumulation distribution by trust Z in the taxable year 1976 and under section 666(a) will be deemed distributed on the last day of the preceding taxable years 1972, 1973, and 1974.

(2) From the sum of the taxes for the prior taxable years attributable to the section 666 amounts (computed in accordance with subparagraph (1) of this paragraph), subtract so much of the amount of taxes deemed distributed to the beneficiary under §§1.666(b)-1A and 1.666(c)-1A as does not exceed such sum. The resulting amount, if any, is the partial tax, computed under the exact method, for the taxable year in which the accumulation distribution is paid, credited, or required to be distributed to the beneficiary.

(3) The provisions of this paragraph may be illustrated by the following example:

(c) Computation of tax by the short- cut method.

(1) The tax referred to in paragraph (a)(2) of this section is computed as follows:

(i) First, determine 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. For purposes of the preceding sentence, the preceding taxable years of a trust that has received an accumulation distribution from another trust shall include the taxable years of such other trust in which an amount was deemed distributed in such accumulation distribution. For example, assume trust Z, a calendar year trust, received in its taxable year 1975 an accumulation distribution from trust Y, a calendar year trust, that included undistributed net income of trust Y for the taxable years 1972, 1973, and 1974. To the extent an accumulation distribution made by trust Z in its taxable year 1976 includes such undistributed net income, it shall be considered an accumulation distribution by trust Z in the taxable year 1976 and under section 666(a) will be deemed distributed on the last day of the preceding taxable years 1972, 1973, and 1974. For purposes of this subparagraph, such number of preceding taxable years of the trust shall not include any preceding taxable year of the trust in which the undistributed net income deemed distributed is less than 25 percent of (a) the total amounts deemed under section 666(a) to be undistributed net income from preceding taxable years divided by (b) the number of such preceding taxable years of the trust on the last day of which an amount is deemed under section 666(a) to have been distributed without application of this sentence. For example, assume that an accumulation distribution of $90,000 made to a beneficiary in 1979 is deemed distributed in the amounts of $29,000 in each of the years 1972, 1973, and 1974, and $3,000 in 1975. The number of preceding taxable years on the last day of which an amount was deemed distributed without reference to the second sentence of this subparagraph is four. However, the distribution deemed made in 1975 ($3,000) is less than $5,625, which is 25 percent of (a) the total undistributed net income deemed distributed under section 666(a) ($90,000) divided by (b) the number of such preceding taxable years (4), or $22,500. Therefore, for purposes of this subparagraph the accumulation distribution is deemed distributed in only 3 preceding taxable years (1972, 1973, and 1974).

(ii) Second, divide the amount (representing the accumulation distribution and taxes deemed distributed) required under section 668(a) to be included in the income of the beneficiary for the taxable year by 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 (determined as provided in subdivision (i) of this subparagraph). The amount determined under this subdivision, including taxes deemed distributed, consists of the same proportion of each class of income as the total of each class of income deemed distributed in the accumulation distribution bears to the total undistributed net income from such preceding taxable years deemed distributed in the accumulation distribution. For example, assume that an amount of $50,000 is deemed distributed under section 666(a) from undistributed net income of 5 preceding taxable years of the trust, and consists of $25,000 of interest, $15,000 of dividends, and $10,000 of net rental income. Taxes attributable to such amounts in the amount of $10,000 are also deemed distributed. The amount determined under this subdivision, $12,000 ($50,000 income plus $10,000 tax divided by 5 years), is deemed to consist of $6,000 in interest, $3,600 in dividends, and $2,400 in net rental income.

(iii) Third, compute the tax of the beneficiary for each of the 3 taxable years immediately preceding the year in which the accumulation distribution is paid, credited, or required to be distributed to him,

(a) With the inclusion in gross income of the beneficiary for each of such 3 years of the amount determined under subdivision (ii) of this subparagraph, and

(b) Without such inclusion.

The difference between the amount of tax computed under (a) of this subdivision for each year and the amount computed under (b) of this subdivision for that year is the additional tax resulting from the inclusion in gross income for that year of the amount determined under subdivision (ii) of this subparagraph. For example, assume that a distribution of $12,000, is includible in the income of each of the beneficiary's 3 preceding taxable years when his income (without the inclusion of the accumulation distribution) was $20,000, $30,000, and $40,000. The inclusion of $12,000 in income would produce taxable income of $32,000, $42,000, and $52,000, and the tax attributable to such increases would be $4,000, $5,000, and $6,000, respectively.

(iv) Fourth, add the additional taxes resulting from the application of subdivision (iii) of this subparagraph and then divide this amount by 3. For example, if these additional taxes are $4,000, $5,000, and $6,000 for the 3 preceding taxable years, this amount would be $5,000 ($4,000 + $5,000 + $6,000 divided by 3).

(v) Fifth, the resulting amount is then multiplied by 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 (previously determined under subdivision (i) of this subparagraph). For example, if an amount is deemed distributed for 5 preceding taxable years, the resulting amount would be five times the $5,000 amount.

(vi) Sixth, the resulting amount, less so much of the amount of taxes deemed distributed to the beneficiary under §§1.666(b)-1A and 1.666(c)-1A as does not exceed such resulting amount, is the tax under the short-cut method provided in section 668(b)(1)(B).

(2) The computation of the tax by the short-cut method may be illustrated by the following example:

(d) Disallowance of short-cut method. If, in any prior taxable year of the beneficiary in which any part of the accumulation distribution of undistributed net income is deemed to have been distributed under section 666(a) to such beneficiary, any part of prior accumulation distributions of undistributed net income by each of two or more other trusts is deemed under section 666(a) to have been distributed to such beneficiary, then the short-cut method under paragraph (c) of this section may not be used and the partial tax imposed by section 668(a)(2) shall be computed only under the exact method under paragraph (b) of this section. For example, assume that, in 1978, trust X makes an accumulation distribution of undistributed net income to A, who is on the calendar year basis, and part of the accumulation distribution is deemed under section 666(a) to have been distributed on March 31, 1974. In 1977, A had received an accumulation distribution of undistributed net income from both trust Y and trust Z. Part of the accumulation distribution from trust Y was deemed under section 666(a) to have been distributed to A on June 30, 1974, and part of the accumulation distribution from trust Z was deemed under section 666(a) to have been distributed to A on December 31, 1974. Because there were portions of accumulation distributions of undistributed net income from two other trusts deemed distributed within the same prior taxable year of A (1974), the 1978 accumulation distribution from trust X may not be computed under the short-cut method provided in paragraph (c) of this section. Therefore the exact method under paragraph (b) of this section must be used to compute the tax imposed by section 666(a)(2).

[T.D. 7204, 37 FR 17149, Aug. 25, 1972]