Tenn. Code § 17-526
A member who is an employee, who has completed eight (8) years of credited service, and who has become disabled as defined in § 17-525 shall be eligible, upon retirement from the active employment of the employer on his disability retirement date, which shall be the first day of the month following the determination by the board that he is disabled, to receive a disability benefit as provided in this section. The monthly disability retirement benefit payable on a member's disability retirement date, as defined in this section, and on the first day of each month thereafter during the period of his disability, as defined in § 17-525, and during his lifetime, shall be computed in the same manner set forth in § 17-522 except that such computation shall be made as of his disability retirement date and the amount of such benefit shall not be less than one-fourth (¼) of his average earnings per month. A member shall also receive, upon retirement on his disability retirement date, as defined in this section, a lump sum benefit equal to six (6) months of his monthly disability retirement benefits.
T.C.A. § 17-526