Code of Federal Regulations Title 26. Internal Revenue § 26.31.3121(b)–4 Employment;  excepted services in general

(a) Services performed by an employee for an employer do not constitute employment for purposes of the taxes if they are specifically excepted from employment under any of the numbered paragraphs of section 3121(b). Services so excepted do not constitute employment for purposes of the taxes even though they are performed within the United States, or are performed outside the United States on or in connection with an American vessel or American aircraft, or are performed outside the United States by a citizen of the United States for an American employer. If not otherwise provided in the regulations relating to the numbered paragraphs of section 3121(b), such regulations apply to services performed after 1954.

(b) The exception attaches to the services performed by the employee and not to the employee as an individual;  that is, the exception applies only to the services in an excepted class rendered by the employee.

Example. A is an individual who is employed part time by B to perform services which are specifically excepted from employment under one of the numbered paragraphs of section 3121(b). A is also employed by C part time to perform services which constitute employment. While no tax liability is incurred with respect to A's remuneration for services performed in the employ of B (the services being excepted from employment), the exception does not embrace the services performed by A in the employ of C (which constitute employment) and the taxes attached with respect to the wages (see § 31.3121(a)–1) for such services.

(c) For provisions relating to the circumstances under which services which are excepted are nevertheless deemed to be employment, and relating to the circumstances under which services which are not excepted are nevertheless deemed not to be employment, see § 31.3121(c)–1.