Tennessee Code Title 8. Public Officers and Employees § 8-35-307

(a) Should a teacher who is a member of the retirement system enter the employ of an employer operating a local retirement fund in which the teacher is eligible for membership, the teacher shall cease to contribute to the retirement system and become subject to the local retirement fund, but shall not lose previous accrued credits in the retirement system so long as the teacher continues in the service of such employer.

(b) Any teacher who is a member of a local retirement fund and who had teaching service in the Tennessee teachers' retirement system or the Tennessee consolidated retirement system may establish this service in the Tennessee consolidated retirement system at any time prior to retirement; provided, that the teacher has taught at least ten (10) years in the public schools of Tennessee; and provided further, that the teacher makes redeposit of the contributions withdrawn plus interest at the rate provided for in § 8-37-214. Any teacher who is eligible to receive retirement credit in the local fund for service withdrawn from the Tennessee consolidated retirement system or the superseded system shall not be entitled to establish retirement credit for the withdrawn service in this system.