26 C.F.R. § 1.652(a)-1
Subject to the rules in §§ 1.652(a)-2 and 1.652(b)-1 , a beneficiary of a simple trust includes in his gross income for the taxable year the amounts of income required to be distributed to him for such year, whether or not distributed. Thus, the income of a simple trust is includible in the beneficiary's gross income for the taxable year in which the income is required to be distributed currently even though, as a matter of practical necessity, the income is not distributed until after the close of the taxable year of the trust. See § 1.642(a)(3) -2 with respect to time of receipt of dividends. See § 1.652(c)-1 for treatment of amounts required to be distributed where a beneficiary and the trust have different taxable years. The term income required to be distributed currently includes income required to be distributed currently which is in fact used to discharge or satisfy any person's legal obligation as that term is used in § 1.662(a)-4 .
26 C.F.R. §1.652(a)-1