Md. Code, Business Occupations and Professions § 17–517

(a) Each licensed real estate broker who is a resident of the State shall maintain an office in the State.

(b) Each licensed real estate broker who is a nonresident of the State shall maintain an office in this State if the state in which the nonresident broker resides requires a resident of this State who is licensed in the other state to maintain an office in that state.