Somerset County ADU Mandate: Preparing for the October 2026 Compliance Deadline

§ 4-504(a)(1) of Maryland's Land Use article imposes a statutory deadline of October 1, 2026 for every county and municipality with planning and zoning authority to adopt a local law authorizing accessory dwelling units (ADUs) on land zoned for single-family residential use. According to ADU Zoning, the mandate derives from HB 1466, signed by Governor Moore on April 22, 2025 and effective October 1, 2025 as Chapter 197, which added Title 4, Subtitle 5 — "Accessory Dwelling Units" — to the Annotated Code. Somerset County, a charter county reached through § 1-401(b), falls within the same compliance window.

Statutory Scope and Conditions

• The operative sentence reads: "On or before October 1, 2026, each legislative body shall adopt a local law authorizing the development of accessory dwelling units on land zoned for single-family residential use in accordance with this section."
• § 4-504(b) extends the local law to all single-family-zoned land in the jurisdiction, subject to two conditions: the developer must own the lot and hold exclusive use rights, and the parcel cannot be otherwise barred from new dwelling units by limits on safe drinking water, sewage disposal, or fire, flood, or landslide risks.
• Charter counties — including Montgomery, Prince George's, Baltimore, Howard, Anne Arundel, Harford, and Somerset — are explicitly in scope.

Permitted Local Restrictions and Out-of-Scope Limits

• § 4-504(a)(2) authorizes local safety standards for ADUs.
• A legislative body may prohibit full or partial conversion of an accessory structure into an ADU where the only vehicular access to that structure is from an alley — a provision with practical reach inside older Somerset housing stock.
• A local law that restricts ADUs to a narrow subset of single-family parcels departs from the statute's plain scope; the statute does not obviously endorse that approach.
• Beyond safety standards and the alley rule, the list of permitted local restrictions is short.

Covenants, HOAs, and the Compliance Clock

• A use restriction in an instrument transferring or selling real property may no longer impose limits on ADU development or use on single-family-zoned land.
• An HOA governing body is authorized to treat an ADU as a separate lot for voting and assessment purposes.
• The October 1, 2026 deadline is statutory, not advisory. Somerset County's legislative body must adopt the authorizing local law by that date.
• Property owners should verify zoning classification, deed-restriction language, and HOA bylaws before assuming eligibility. Safety standards, alley-access rules, and documented infrastructure limits remain the only statutory grounds on which an ADU may be excluded.