There is included in the gross income of a beneficiary of an estate or complex trust the sum of:
§ 1.662(a)-1(a) Amounts of income required to be distributed currently to him, and
§ 1.662(a)-1(b) All other amounts properly paid, credited, or required to be distributed to him
by the estate or trust. The preceding sentence is subject to the rules contained in § 1.662(a)-2 (relating to currently distributable income), § 1.662(a)-3 (relating to other amounts distributed), and §§ 1.662(b)-1 and 1.662(b)-2 (relating to character of amounts). Section 662 has no application to amounts excluded under section 663(a).