27 Miss. Code. R. 210-12-101
Prior to July 1, 1980, statutory law prohibited any person who was retired from service under any retirement system of the State of Mississippi operating for state, county or municipal employees and who was receiving retirement benefits thereunder from being eligible to participate in the state retirement annuity coverage. Thus, prior to this date, retirants receiving a retirement allowance under any retirement plan of this State, or who received a retirement allowance or pension on or after April 15, 1952, from any plan of this State were not eligible for Article II of SB 273, Laws of 1952, [now Article III beginning at Miss. Code Ann. § 25-11-101 et seq. (1972, as amended)]
Effective July 1, 1980, the statutory prohibition was removed and retirants of another system administered for state, county, or municipal employees had the option to participate in state retirement annuity coverage. Retirees from other systems hired after July 1, 1980, are covered automatically for state retirement annuity coverage.
27 Miss. Code. R. 210-12-101