26 CFR § 31.3401(a)-3 - Amounts deemed wages under voluntary withholding agreements.
(a) In general. Notwithstanding the exceptions to the definition of wages specified in section 3401(a) and the regulations thereunder, the term “wages” includes the amounts described in paragraph (b)(1) of this section with respect to which there is a voluntary withholding agreement in effect under section 3402(p). References in this chapter to the definition of wages contained in section 3401(a) shall be deemed to refer also to this section (§ 31.3401(a)-3).
(b) Remuneration for services.
(1) Except as provided in subparagraph (2) of this paragraph, the amounts referred to in paragraph (a) of this section include any remuneration for services performed by an employee for an employer which, without regard to this section, does not constitute wages under section 3401(a). For example, remuneration for services performed by an agricultural worker or a domestic worker in a private home (amounts which are specifically excluded from the definition of wages by section 3401(a) (2) and (3), respectively) are amounts with respect to which a voluntary withholding agreement may be entered into under section 3402(p). See §§ 31.3401(c)-1 and 31.3401(d)-1 for the definitions of “employee” and “employer”.
(2) For purposes of this paragraph, remuneration for services shall not include amounts not subject to withholding under § 31.3401(a)-1(b)(12) (relating to remuneration for services performed by a permanent resident of the Virgin Islands), § 31.3401(a)-2(b) (relating to fees paid to a public official), section 3401(a)(5) (relating to remuneration for services for foreign government or international organization), section 3401(a)(8)(B) (relating to remuneration for services performed in a possession of the United States (other than Puerto Rico) by citizens of the United States), section 3401(a)(8)(C) (relating to remuneration for services performed in Puerto Rico by citizens of the United States), section 3401(a)(11) (relating to remuneration other than in cash for service not in the course of employer's trade or business), section 3401(a)(12) (relating to payments from or to certain tax-exempt trusts, or under or to certain annuity plans or bond purchase plans), section 3401(a)(14) (relating to group-term life insurance), section 3401(a)(15) (relating to moving expenses), or section 3401(a)(16)(A) (relating to tips paid in any medium other than cash).