Miss. Code Ann. § 25-11-413: Miss. Code Ann. § 25-11-413

Any person electing to participate in the optional retirement program shall be ineligible for membership in the Public Employees' Retirement System of Mississippi so long as he is employed in a position for which the optional retirement program is available. If an optional retirement program participant assumes a position in state service other than as an employee of a state institution of higher learning, he must at that time begin membership in the Public Employees' Retirement System of Mississippi in accordance with Article 3 of this chapter.