Tenn. Code Ann. § 8-36-505

Any member eligible for a disability retirement may set the effective date of such member's retirement at any date within one hundred fifty (150) days before or after the date such member's application is filed with the board; provided, that such effective date of retirement follows the date of such member's separation from service, the date on which the member's temporary disability benefits under the workers' compensation law cease, or the date on which the member became totally and permanently disabled, whichever is later.