Tenn. Code § 17-522
Each member shall be eligible upon retirement on his normal retirement date to receive a benefit as provided in this section. The benefits provided in this section shall also be paid to all members of the retirement system for county paid judges who retired prior to May 17, 1967. The monthly normal retirement benefit shall be payable on a member's normal retirement date and on the first day of each month thereafter during his lifetime and shall be computed as of his normal retirement date as one-twelfth (1/12) of the product of (a) and (b):
In no event, however, shall a member receive upon retirement a benefit from a retirement system greater than seventy-five per cent (75%) of average earnings.
Notwithstanding any other provisions in this chapter, whenever a member retires on his normal retirement date having twenty-four (24) years of credited service, he shall be entitled to receive a monthly retirement benefit equal to one-twelfth (1/12) of seventy-five per cent (75%) of his average earnings.
T.C.A. § 17-522