40 ILCS 5/18-121
A judge who filed a notice of election not to participate shall become a participant upon filing with the board before July 1, 1992, a written recision of such notice. The recision shall state that such person is then a judge, his or her present age, and previous records of service as a judge. After 3 years of service as a participant, the judge may obtain credit for all service as a judge prior to the date of participation by paying into the system the contributions that he or she would have made as a participant at the rates in effect during such service, together with interest at the rate of 4% per annum compounded annually from the date the contributions would have been due to the date of payment. Upon compliance, he or she shall receive credit for all service rendered as a judge prior to the date of becoming a participant. The time and manner of making such additional contributions, including interest, shall be prescribed by the board.
Except as otherwise provided, a judge becoming a participant by a recision of an election not to participate, shall be governed by the provisions of this Article in effect on the date of the recision.
40 ILCS 5/18-121