For purposes of this section, the term “compensation” includes earned income (as defined in section
401
(c)(2)). The term “compensation” does not include any amount received as a pension or annuity and does not include any amount received as deferred compensation. The term “compensation” shall include any amount includible in the individual’s gross income under section
71 with respect to a divorce or separation instrument described in subparagraph (A) of section
71
(b)(2). For purposes of this paragraph, section
401
(c)(2) shall be applied as if the term trade or business for purposes of section
1402 included service described in subsection (c)(6). The term compensation includes any differential wage payment (as defined in section
3401
(h)(2)).