26 CFR § 1.1402(c)-2 - Public office.
(a) In general -
(2) Fee basis public officials -
(i) In general. If an individual receives fees after 1967 for the performance of the functions of a public office of a State or a political subdivision thereof for which he is compensated solely on a fee basis, and if the service performed in such office is eligible for (but is not made the subject of) an agreement between the State and the Secretary of Health, Education, and Welfare pursuant to section 218 of the Social Security Act to extend social security coverage thereto, the service for which such fees are received constitutes a trade or business within the meaning of section 1402(c) and § 1.1402(c)-1. If an individual performs service for a State or a political subdivision thereof in any period in more than one position, each position is treated separately for purposes of the preceding sentence. See also paragraph (f) of § 1.1402(c)-3 relating to the performance of service by an individual as an employee of a State or a political subdivision thereof in a position compensated solely on a fee basis.
(ii) Election with respect to fees received in 1968.
(A) Any individual who in 1968 receives fees for service performed by him with respect to the functions of a public office of a State or a political subdivision thereof in any period in which the functions are performed in a position compensated solely on a fee basis may elect, if the performance of the service for which such fees are received constitutes a trade or business pursuant to the provisions of subdivision (i) of this subparagraph, to have such performance of service treated as excluded from the term “trade or business” for the purpose of the tax on self-employment income, pursuant to the provisions of section 122(c)(2) of the Social Security Amendments of 1967 (as quoted in § 1.1402(c)). Such election shall not be limited to service to which the fees received in 1968 are attributable but must also be applicable to service (if any) in subsequent years which, except for the election, would constitute a trade or business pursuant to the provisions of subdivision (i) of this subparagraph. An election made pursuant to the provisions of this subparagraph is irrevocable.
(B) The election referred to in subdivision (ii)(A) of this subparagraph shall be made by filing a certificate of election of exemption (Form 4415) on or before the due date of the income tax return (see section 6072), including any extension thereof (see section 6081), for the taxable year of the individual making the election which begins in 1968. The certificate of election of exemption shall be filed with an internal revenue office in accordance with the instructions on the certificate.
(b) Meaning of public office. The term “public office” includes any elective or appointive office of the United States or any possession thereof, of the District of Columbia, of a State or its political subdivisions, or a wholly-owned instrumentality of any one or more of the foregoing. For example, the President, the Vice President, a governor, a mayor, the Secretary of State, a member of Congress, a State representative, a county commissioner, a judge, a justice of the peace, a county or city attorney, a marshal, a sheriff, a constable, a registrar of deeds, or a notary public performs the functions of a public office. (However, the service of a notary public could not be made the subject of a section 218 agreement under the Social Security Act because notaries are not “employees” within the meaning of that section. Accordingly, such service does not constitute a trade or business.)