O.C.G.A. § 47-23-120: No abridgement of rights under predecessor retirement provisions.

This chapter shall not deny or abridge any right, benefit, option, credit, or election to which any person was entitled under a predecessor retirement system on June 30, 1998, and the board of trustees is authorized and directed to provide by regulation for the continuation of any such right, benefit, option, credit, or election not otherwise covered in this chapter. All other persons who become members shall be subject to the provisions of this chapter.