Md. Code, State Personnel and Pensions § 22–307

A member of the Employees’ Retirement System who had served as an elected or appointed official of the State or a participating governmental unit may receive service credit for the previous service as an official including service before the establishment of the Employees’ Retirement System, if the member makes a single payment, within the period determined by the Board of Trustees, of the member contributions, plus interest, that the Board of Trustees considers appropriate.