26 CFR §1.643(a)-3

1. (a)In general. Except as provided in § 1.643(a)-6 and paragraph (b) of this section, gains from the sale or exchange of capital assets are ordinarily excluded from distributable net income and are not ordinarily considered as paid, credited, or required to be distributed to any beneficiary.
2. (b)Capital gains included in distributable net income. Gains from the sale or exchange of capital assets are included in distributable net income to the extent they are, pursuant to the terms of the governing instrument and applicable local law, or pursuant to a reasonable and impartial exercise of discretion by the fiduciary (in accordance with a power granted to the fiduciary by applicable local law or by the governing instrument if not prohibited by applicable local law)—
   1. (1)Allocated to income (but if income under the state statute is defined as, or consists of, a unitrust amount, a discretionary power to allocate gains to income must also be exercised consistently and the amount so allocated may not be greater than the excess of the unitrust amount over the amount of distributable net income determined without regard to this subparagraph § 1.643(a)-3(b));
   2. (2)Allocated to corpus but treated consistently by the fiduciary on the trust's books, records, and tax returns as part of a distribution to a beneficiary; or
   3. (3)Allocated to corpus but actually distributed to the beneficiary or utilized by the fiduciary in determining the amount that is distributed or required to be distributed to a beneficiary.
3. (c)Charitable contributions included in distributable net income. If capital gains are paid, permanently set aside, or to be used for the purposes specified in section 642(c), so that a charitable deduction is allowed under that section in respect of the gains, they must be included in the computation of distributable net income.
4. (d)Capital losses. Losses from the sale or exchange of capital assets shall first be netted at the trust level against any gains from the sale or exchange of capital assets, except for a capital gain that is utilized under paragraph (b)(3) of this section in determining the amount that is distributed or required to be distributed to a particular beneficiary. See § 1.642(h)-1 with respect to capital loss carryovers in the year of final termination of an estate or trust.
5. (e)Examples. The following examples illustrate the rules of this section:
6. (f)Effective date. This section applies for taxable years of trusts and estates ending after January 2, 2004.