(a) There is included in distributable net income any tax-exempt interest excluded from gross income under section 103, reduced by disbursements allocable to such interest which would have been deductible under section 212 but for the provisions of section 265 (relating to disallowance of deductions allocable to tax-exempt income).

(b) If the estate or trust is allowed a charitable contributions deduction under section 642(c), the amounts specified in paragraph (a) of this section and § 1.643(a)-6 are reduced by the portion deemed to be included in income paid, permanently set aside, or to be used for the purposes specified in section 642(c). If the governing instrument or local law specifically provides as to the source out of which amounts are paid, permanently set aside, or to be used for such charitable purposes, the specific provision controls for Federal tax purposes to the extent such provision has economic effect independent of income tax consequences. See § 1.652(b)-2(b). In the absence of such specific provisions in the governing instrument or local law, an amount to which section 642(c) applies is deemed to consist of the same proportion of each class of the items of income of the estate or trust as the total of each class bears to the total of all classes. For illustrations showing the determination of the character of an amount deductible under section 642(c), see Examples 1 and 2 of § 1.662(b)-2 and § 1.662(c)-4(e).