Tex. Gov't Code § 830.105
(a) A person terminates participation in the optional retirement program, without losing any accrued benefits, by:
Acts 1981, 67th Leg., p. 1876, ch. 453, Sec. 1, eff. Sept. 1, 1981.
Amended by Acts 1981, 67th Leg., 1st C.S., p. 208, ch. 18, Sec. 37, eff. Nov. 10, 1981;
Acts 1987, 70th Leg., ch. 173, Sec. 1, eff. Aug. 31, 1987. Renumbered from Vernon's Ann.Civ.St. Title 110B, Sec. 36.105 and amended by Acts 1989, 71st Leg., ch. 179, Sec. 1, eff. Sept. 1, 1989.