Maryland Code, Corporations and Associations § 5-105

(1) Require an individual employed by a professional corporation to be licensed to perform services for the corporation if a license is not otherwise required;

(2) Prohibit a licensed individual from rendering professional services in his individual capacity although he is a stockholder, director, officer, employee, or agent of a domestic or foreign professional corporation; or

(3) Prohibit an individual licensed in another state from rendering professional services for a domestic or foreign professional corporation in the State if not prohibited by the licensing unit in the State with jurisdiction over the professional service.