40 ILCS 5/21-104

Any noncorporate public entity may by resolution of its governing body elect to have its employees covered by the Social Security Act in the same manner and subject to the same conditions as are set forth in Sections 21-103 and 21-105, but subject to the following additional conditions: (a) that the agreement by which the entity was created or an amendment to that agreement authorizes the entity to provide for the extension of Social Security benefits to its employees; and (b) that Social Security contributions due on wages covered under the agreement paid prior to January 1, 1987 and wage reports required for calendar years prior to 1987 are submitted to the State Agency along with the coverage agreement executed by the entity.