Tennessee Code Title 8. Public Officers and Employees § 8-35-109

Any person who becomes a state judge, a county judge, a county official, a commissioner, a county chair, an elected or appointed official of the general assembly, or any district attorney general and any assistant thereto by whatever name called, on or after July 1, 1983, shall not become a member of the retirement system, unless such person elects to become a member of the system and is otherwise eligible for membership. The election shall be made in the manner prescribed by the retirement system and shall be filed with the retirement system.