Maryland Code, Local Government § 9-113

(a) In this section, “chief executive officer” means:

(b) This section applies only to Baltimore City and Montgomery County.

(c) Except as provided in subsection (d) of this section, a candidate for chief executive officer shall be a resident of the county for at least 6 months before the general election for chief executive officer.

(d) If the charter of a county contains a durational residency requirement that is longer than 6 months, the longer durational residency requirement shall be retained if the governing body of the county reaffirms the requirement by enactment of an ordinance no later than 4 weeks before the filing deadline specified in § 5-303(a) of the Election Law Article.