Tennessee Code Title 8. Public Officers and Employees § 8-35-254

(a) A political subdivision participating in the retirement system prior to July 1, 2012, may continue to do so under the terms and conditions in effect on July 1, 2012, without taking any additional action.

(b) Notwithstanding any other law to the contrary and only as it applies to new employees hired on or after July 1, 2012, the political subdivision may require employee contributions of zero percent (0%) of the employees' earnable compensation, or may require employee contributions of two and five-tenths percent (2.5%) of the employees' earnable compensation, or employee contributions of five percent (5%) of the employees' earnable compensation. Any employee contributions assumed or paid by a political subdivision on behalf of its employees shall not be credited to the individual account balances of the employees. In order to effectuate a change in the employee contributions, the political subdivision must pass a resolution legally adopted by a majority of the membership of the chief governing body of the subdivision. Any such resolution shall set forth the effective date of the change in employee contributions; provided, that the date shall be on the first day of any quarter following a minimum of three (3) months' notice to the retirement system.