Illinois Statutes Chapter 40. Pensions § 5/9-179.2. Other governmental service--Former County Service

(a) The employee shall pay to this fund, while in the service of such county, or while in the service of a governmental unit whose retirement system has adopted the “Retirement Systems Reciprocal Act”, such amounts, including interest at the effective rate, as he would have paid to this fund, on the basis of his salary in effect during the service rendered to such other “governmental unit” at the rates prescribed in this Article 9 for the periods of such service to the end that such service shall be considered as service rendered to such county, with all the rights and conditions attaching to such service and payments; and

(b) this Section shall not be applicable to any period of such service for which the employee retains credit in any other public annuity and benefit fund established by Act of the Legislature of this State and in operation for employees of such other “governmental unit” from which such employee was transferred.