Tenn. Code § 8-3517
Effective July 1, 1969, and each succeeding July 1, the initial service retirement allowance paid on retirement to any member retired prior to July 1, 1969 who, at the date of his retirement, had attained age fifty-five (55) and completed at least twenty (20) years of credited service, shall be increased by one and one-half per cent (1 ½%) of such initial allowance for each year that the member has been retired after his attainment of age sixty-five (65), but the aggregate of such annual increments to any retired member's allowance shall not exceed thirty per cent (30%) of his initial service retirement allowance. The provisions of this section shall not be effective in any case where the application thereof results in a lesser allowance to any retired member than the application of the provisions of § 8-3502.
T.C.A. § 8-3517