Miss. Code § 21-31-61
The provisions of Sections 21-31-51 through 21-31-75 shall include all administrative and other employees on a monthly salary basis. All appointments to and promotions in said departments shall be made solely on merit, efficiency and fitness which may be ascertained by open competitive examination and impartial investigation. No person shall be reinstated in, or transferred, suspended or discharged from, any place, position or employment contrary to the provisions of Sections 21-31-51 through 21-31-75.
All incumbents and future appointees shall be subject to civil service, except, however, those appointees now and hereafter serving as extra members, which employees shall be subject to removal for replacement by any person now or hereafter serving in the armed services; or, if temporarily employed, the commission shall have authority to so determine and replace with a new employee who shall be subject to the provisions of Sections 21-31-51 through 21-31-75.
The provisions of Sections 21-31-51 through 21-31-75 shall not include any new employee who has not successfully completed all requirements necessary to earn regular or permanent status as a municipal employee.
Miss. Code § 21-31-61