40 ILCS 5/7-139.12
A person employed by the Chicago Metropolitan Agency for Planning (formerly the Regional Planning Board) on the effective date of this Section who was a member of the State Employees' Retirement System of Illinois as an employee of the Chicago Area Transportation Study may apply for transfer of his or her creditable service as an employee of the Chicago Metropolitan Agency for Planning upon payment of (1) the amounts accumulated to the credit of the applicant for such service on the books of the Fund on the date of transfer and (2) the corresponding municipality credits, including interest, on the books of the Fund on the date of transfer. Participation in this Fund with respect to the transferred credits shall terminate on the date of transfer.
40 ILCS 5/7-139.12