Illinois Statutes Chapter 40. Pensions § 5/7-138. Employees covered under the Federal Social Security Act and effective dates

(a) Each person who was an employee of a municipality or participating instrumentality covered as of January 1, 1956, and employed by such municipality or participating instrumentality on December 31, 1957, shall be considered a covered employee as of January 1, 1956, or the date employment with such municipality or participating instrumentality began, whichever is later;

(b) Each person who was an employee of a municipality or participating instrumentality covered as of January 1, 1956, who was not employed by such municipality or participating instrumentality on December 31, 1957, shall be considered a covered employee as of the first date of employment after such date;

(c) Each person who was an employee of a municipality or participating instrumentality becoming covered after December 31, 1957, shall be considered a covered employee on the date the municipality or participating instrumentality becomes a covered municipality or participating instrumentality or on the first date of employment, whichever is later;

(d) Each person who performs service for a municipality or participating instrumentality defined as covered transportation service under Section 210 of the Federal Social Security Act  2 if he (1) meets the requirements of Section 7-137 of this Act, (2) is employed by a municipality or participating instrumentality which has elected to participate and has been accepted for participation, and (3) is subject to the Federal Insurance Contributions Act,  3 shall be considered a covered employee for the purpose of computing benefits under this Article, but no contributions need be made for Social Security purposes under this Article so long as contributions are being made under the Federal Insurance Contributions Act in respect to such service.