26 CFR § 1.668(a)-1 - Amounts treated as received in prior taxable years; inclusion in gross income.
(a) Section 668(a) provides that the total of the amounts treated under section 666 as having been distributed by the trust on the last day of a preceding taxable year of the trust shall be included in the gross income of the beneficiary or beneficiaries receiving them. The total of such amounts is includible in the gross income of each beneficiary to the extent the amounts would have been included under section 662 (a)(2) and (b) if the total had actually been paid by the trust on the last day of such preceding taxable year. The total is included in the gross income of the beneficiary for the taxable year of the beneficiary in which such amounts are in fact paid, credited, or required to be distributed unless the taxable year of the beneficiary differs from the taxable year of the trust (see section 662(c) and the regulations thereunder). The character of the amounts treated as received by a beneficiary in prior taxable years, including taxes deemed distributed, in the hands of the beneficiary is determined by the rules set forth in section 662(b) and the regulations thereunder. See paragraphs (h)(1)(ii) and (j)(1)(ii) of § 1.668(b)-2.
(b) The total of the amounts treated under section 666 as having been distributed by the trust on the last day of a preceding taxable year of the trust are included as prescribed in paragraph (a) of this section in the gross income of the beneficiary even though as of that day the beneficiary would not have been entitled to receive them had they actually been distributed on that day.
(c) Any deduction allowed to the trust in computing distributable net income for a preceding taxable year (such as depreciation, depletion, etc.) is not deemed allocable to a beneficiary because of amounts included in a beneficiary's gross income under this section since the deduction has already been utilized in reducing the amount included in the beneficiary's income.