Tenn. Code § 8-3417
Any person who was an employee in the services of the state of Tennessee, or of the educational system of the state, or any county, city, or special school district, receiving funds from the state of Tennessee, and who is or was granted military leave and who returns to state employment within six (6) months after date of separation and becomes a member of the state retirement system shall be allowed credit as to prior service for the period of military service rendered by him when this country was at war, provided that the member shall contribute for that prior service as if his earnings during military service had been equal to his first year's compensation after his reemployment by the state, such contributions to be made as in the case of other prior service contributions. Notwithstanding any provisions of the law to the contrary, any member who returns to state service within eighty (80) months after returning from military service provided the member was in service less than two (2) years and provided the member shall make back contributions as set out in § 8-3417 shall claim such services.
T.C.A. § 8-3417