Tex. Government Code § 813.301: CREDITABLE MILITARY SERVICE.

(a) Military service creditable in the retirement system is active federal duty as a member of the armed forces of the United States.

(b) A member may establish one month of service credit for each month or fraction of a month of duty, but not more than 60 months of service credit in the retirement system for military service.

Acts 1981, 67th Leg., p. 1876, ch. 453, Sec. 1, eff. Sept. 1, 1981. Renumbered from Vernon's Ann.Civ.St. Title 110B, Sec. 23.301 by Acts 1989, 71st Leg., ch. 179, Sec. 1, eff. Sept. 1, 1989. Amended by Acts 1991, 72nd Leg., ch. 850, Sec. 5, eff. Sept. 1, 1991; Acts 1997, 75th Leg., ch. 1048, Sec. 6, eff. Sept. 1, 1997.