Md. Code, Land Use § 1–506

(a) Subject to subsections (b), (c), and (d) of this section, a local jurisdiction that chooses to adopt growth tiers is not required to adopt all of the tiers.

(b) A municipal corporation that exercises planning and zoning authority shall adopt Tier I and may adopt Tier II.

(c) A county shall adopt Tiers I, III, and IV, and may adopt Tier II.

(d) If a local jurisdiction does not adopt all of the tiers authorized under this section, the local jurisdiction shall document the reasons the jurisdiction is not adopting a particular tier.