(a) Periods of exclusion—(1) Taxable years ending before 1955. For taxable years ending before 1955, an individual is not engaged in carrying on a trade or business with respect to the performance of service in the exercise of his profession as a physician, lawyer, dentist, osteopath, veterinarian, chiropractor, naturopath, optometrist, Christian Science practitioner, architect, certified public accountant, accountant registered or licensed as an accountant under State or municipal law, full-time practicing public accountant, funeral director, or professional engineer.

(2) Taxable years ending in 1955. Except as provided in paragraph (b) of this section, for a taxable year ending in 1955 an individual is not engaged in carrying on a trade or business with respect to the performance of service in the exercise of his profession as a physician, lawyer, dentist, osteopath, veterinarian, chiropractor, naturopath, optometrist, or Christian Science practitioner.

(3) Taxable years ending after 1955—(i) Doctors of medicine. For taxable years ending after 1955 and before December 31, 1965, and individual is not engaged in carrying on a trade or business with respect to the performance of service in the exercise of his profession as a doctor of medicine. For taxable years ending after December 30, 1965, an individual is engaged in carrying on a trade or business with respect to the performance of service in the exercise of his profession as a doctor of medicine.

(ii) Christian Science practitioners. Except as provided in paragraph (b)(1) of this section, for taxable years ending after 1955 and before 1968, an individual is not engaged in carrying on a trade or business with respect to the performance of service in the exercise of his profession as a Christian Science practitioner. For provisions relating to the performance of service in taxable years ending after 1967 by an individual in the exercise of his profession as a Christian Science practitioner, see paragraph (b)(2) of this section.

(b) Christian Science practitioner—(1) Certain taxable years ending before 1968; election. For taxable years ending after 1954 and before 1968, a Christian Science practitioner may elect, as provided in § 1.1402(e)(1)-1, to have the Federal old-age, survivors, and disability insurance system established by title II of the Social Security Act extended to service performed by him in the exercise of his profession as a Christian Science practitioner. If an election is made pursuant to § 1.1402(e)(1)-1, the Christian Science practitioner is, with respect to the performance of service in the exercise of such profession, engaged in carrying on a trade or business for each taxable year for which the election is effective. An election by a Christian Science practitioner has no application to service performed by him which is not in the exercise of his profession as a Christian Science practitioner.

(2) Taxable years ending after 1967; exemption. For a taxable year ending after 1967, a Christian Science practitioner is, with respect to the performance of service in the exercise of his profession as a Christian Science practitioner, engaged in carrying on a trade or business unless an exemption under section 1402(e) (see §§ 1.1402(e)-1A through 1.1402(e)-4A) is effective with respect to him for the taxable year during which the service is performed. An exemption which is effective with respect to a Christian Science practitioner has no application to service performed by him which is not in the exercise of his profession as a Christian Science practitioner.

(c) Meaning of terms. The designations in this section are to be given their commonly accepted meanings. For taxable years ending after 1955, an individual who is a doctor of osteopathy, and who is not a doctor of medicine within the commonly accepted meaning of that term, is deemed, for purposes of this section, not to be engaged in carrying on a trade or business in the exercise of the profession of doctor of medicine.

(d) Legal requirements. The exclusions specified in paragraph (a) of this section apply only if the individuals meet the legal requirements, if any, for practicing their professions in the place where they perform the service.

(e) Partnerships. In the case of a partnership engaged in the practice of any of the designated excluded professions, the partnership shall not be considered as carrying on a trade or business for the purpose of the tax on self-employment income, and none of the distributive shares of the income or loss, described in section 702(a)(9), of such partnership shall be included in computing net earnings from self-employment of any member of the partnership. On the other hand, where a partnership is engaged in a trade or business not within any of the designated excluded professions, each partner must include his distributive share of the income or loss, described in section 702(a)(9), of such partnership in computing his net earnings from self-employment, irrespective of whether such partner is engaged in the practice of one or more of such professions and contributes his professional services to the partnership.