(a) Definition—(1) Domestic trusts—(i) In general. For purposes of subpart D, in the case of a trust other than a foreign trust created by a U.S. person, the term preceding taxable year serves to identify and limit the taxable years of a trust to which an accumulation distribution consisting of undistributed net income or undistributed capital gain may be allocated (or “thrown back”) under section 666(a) and 669(a). An accumulation distribution consisting of undistributed net income or undistributed capital gain may not be allocated or “thrown back” to a taxable year of a trust if such year is not a “preceding taxable year.”

(ii) Accumulation distributions. In the case of an accumulation distribution consisting of undistributed net income made in a taxable year beginning before January 1, 1974, any taxable year of the trust that precedes by more than 5 years the taxable year of the trust in which such accumulation distribution was made is not a “preceding taxable year.” Thus, for a domestic trust on a calendar year basis, calendar year 1967 is not a “preceding taxable year” with respect to an accumulation distribution made in calendar year 1973, whereas calendar year 1968 is a “preceding taxable year.” In the case of an accumulation distribution made during a taxable year beginning after December 31, 1973, any taxable year of the trust that begins before January 1, 1969, is not a “preceding taxable year.” Thus, for a domestic trust on a calendar year basis, calendar year 1968 is not a “preceding taxable year” with respect to an accumulation distribution made in calendar year 1975, whereas calendar year 1969 is a “preceding taxable year.”

(iii) Capital gain distributions. In the case of an accumulation distribution that is a capital gain distribution, any taxable year of the trust that (a) begins before January 1, 1969, or (b) is prior to the first year in which income is accumulated, whichever occurs later, is not a “preceding taxable year.” Thus, for the purpose of capital gain distributions and section 669, only taxable years beginning after December 31, 1968, can be “preceding taxable years.” See §1.688(a)-1A(c).

(2) Foreign trusts created by U.S. persons. For purposes of subpart D, in the case of a foreign trust created by a U.S. person, the term “preceding taxable year” does not include any taxable year to which part I of subchapter J does not apply. See section 683 and regulations thereunder. Accordingly, the provisions of subpart D may not, in the case of a foreign trust created by a U.S. person, be applied to any taxable year which begins before 1954 or ends before August 17, 1954. For example, if a foreign trust created by a U.S. person (reporting on the calendar year basis) makes a distribution during the calendar year 1970 of income accumulated during prior years, the earliest year of the trust to which the accumulation distribution may be allocated under such subpart D is 1954, but it may not be allocated to 1953 and prior years, since the Internal Revenue Code of 1939 applies to those years.

(b) Simple trusts. A taxable year of a trust during which the trust was a simple trust (that is, was subject to subpart B) for the entire year shall not be considered a “preceding taxable year” unless during such year the trust received “outside income” or unless the trustee did not distribute all of the income of the trust that was required to be distributed currently for such year. In such event, undistributed net income for such year shall not exceed the greater of the “outside income” or income not distributed during such year. For purposes of this paragraph, the term outside income means amounts that are included in distributable net income of the trust for the year but that are not “income” of the trust as that term is defined in §1.643(b)-1. Some examples of “outside income” are:

(1) Income taxable to the trust under section 691;

(2) Unrealized accounts receivable that were assigned to the trust; and

(3) Distributions from another trust that include distributable net income or undistributed net income of such other trust.

The term outside income, however, does not include amounts received as distributions from an estate, other than income specified in (1) and (2), for which the estate was allowed a deduction under section 661(a). The application of this paragraph may be illustrated by the following examples:

[T.D. 7204, 37 FR 17141, Aug. 25, 1972]