Maryland ADU Laws

Complete 2026 guide to accessory dwelling unit regulations

✓Strong Statewide Law

📋Quick Facts

Size Limit
75% of primary
Owner Occupancy
May be required
Parking
Set locally
Approval Process
✓ By-right
Effective Date
10/1/2025

📜Recent Legislation

HB 1466 / SB 891 (2025) - Accessory Dwelling Units Act of 2025, effective October 1, 2025

⚠️Key Requirements & Restrictions

  • •Max size: 75% of primary dwelling
  • •Applies to charter counties and Baltimore City
  • •Local jurisdictions must adopt ADU laws by October 1, 2026
  • •Must meet public health, safety, and welfare standards

📖Detailed Analysis

Maryland passed comprehensive statewide ADU legislation in 2025 (HB 1466/SB 891) - the Accessory Dwelling Units Act of 2025. Law establishes state policy to promote and encourage ADU creation on single-family lots. Effective October 1, 2025, applies to charter counties and Baltimore City. By October 1, 2026, all local legislative bodies must adopt laws authorizing ADU development. Key provision: ADUs cannot exceed 75% of primary dwelling size. Legislation also addresses HOA restrictions, prohibits unreasonable local barriers, and requires policies that facilitate development while meeting safety standards. Maryland Department of Planning will provide implementation guidance. This makes Maryland the 9th state with strong statewide ADU mandates, joining CA, MA, CO, WA, OR, AZ, CT, and MD. Significant win for housing advocates - leverages existing residential lots for affordable housing.

🔗Official Resources

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⚠️ Disclaimer

The information provided on this website is for general informational purposes only and does not constitute legal, financial, or professional advice. ADU laws, regulations, and requirements vary by jurisdiction and change frequently. While we strive to keep this information accurate and up-to-date, we make no representations or warranties of any kind about the completeness, accuracy, reliability, or suitability of this information. Always consult with qualified local professionals, including attorneys, architects, and your local planning department, before making any decisions regarding ADU construction or investment. Use of this information is at your own risk.

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Last updated: February 2026