During its 2025 session, the Maryland General Assembly passed HB 1466 (“Accessory Dwelling Units – Requirements and Prohibitions”), which codifies state policy supporting development of Accessory Dwelling Units (ADUs), effective October 1, 2025. It also requires that counties and municipalities with planning and zoning authority adopt a local law authorizing ADU development on land with a single-family detached dwelling unit by October 1, 2026.
Common ADU Types
ADUs are smaller, independent dwelling units, attached or detached, located on the same lot as a stand-alone single-family home. ADUs can be converted rooms in existing homes (interior ADUs), additions (attached ADUs), or new/converted stand-alone accessory structures (detached ADUs). With the bill’s passage, it is the policy of the state of Maryland to promote and encourage ADU velopment on land with a primary single-family detached dwelling unit to help meet the state’s housing needs. ADUs also advance the state’s Sustainable Growth Policy and Planning Principles, which endorse a mix of quality housing types and affordability options to accommodate all who want to live in the state.
MDP will release guidance over the next year (see the timeline below) to assist local governments and state agencies with implementation of HB 1466. While the General Assembly identified some common requirements for all local laws, counties and municipalities have substantial flexibility in design of ADU policies to meet the needs of their communities, and many have already adopted ADU ordinances that meet some or all of HB 1466’s requirements. In addition to the research and engagement that will take place over the next year, MDP’s ADU guidance will consider the recommendations of the Accessory Dwelling Unit Policy Task Force Report released in 2024. The bill also includes several additional provisions regarding restrictive covenants, lot and size requirements, and parking restrictions, that MDP guidance will help local governments understand.
Please continue to refer to this webpage as we update it with guidance. For information, suggestions, or requests, please contact Carter Reitman, Lead Housing Planner for the Maryland Department of Planning, at carter.reitman2@maryland.gov.
