ADU Pass
Dorchester County
ADU Pass helps homeowners in Dorchester County, Maryland navigate the permit paperwork for building an accessory dwelling unit. We cover 12 cities and 20 ZIP codes in this county.
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County ADU details
County ADU ordinance
Dorchester County Chapter 155 Article XII permits an 'accessory apartment' only as an interior conversion within a permitted detached single-family dwelling. Detached ADUs, garage conversions, and standalone backyard cottages are NOT enumerated as permitted accessory uses in the county's residential districts. The accessory apartment must occupy no more than 800 sq ft OR one-third of the principal dwelling's total floor area, whichever is less. Within the Chesapeake Bay Critical Area, the principal dwelling must have a minimum 600 sq ft gross floor area before an accessory apartment is allowed. Minimum lot area must be at least 150% of the minimum lot area for the underlying zoning district. The entry and design must preserve the single-family residential appearance, and no external entrance facing a road or street may be added. This is substantially more restrictive than the floor set by Maryland HB 1466 / SB 891 (2025), which requires ADUs up to 75% of the primary dwelling size and explicitly contemplates detached ADUs. Dorchester County must adopt a compliant ordinance by 2026-10-01; as of the lastChecked date below, no county-side amendment has been adopted.
County assessor
Assessment policy: SDAT assesses property at fair market value using the cost, sales, and income approaches. Each property is reviewed on a triennial cycle (every three years); new construction and additions, including ADUs and accessory apartments, trigger an interim supplemental reassessment in the year of completion under the cost approach. Maryland's Homestead Tax Credit caps the year-over-year increase in the taxable assessment on owner-occupied principal residences, but the credit applies only to the primary dwelling - the added ADU square footage is taxed at its full assessed value without the cap.
County overlays (3)
- flood-zone — Sea-level rise vulnerability is documented in 'Sea Level Rise: Technical Guidance for Dorchester County' (Maryland DNR Coast Smart). Accessory apartments added to existing principal dwellings in floodplain require elevation certificates and may trigger substantial-improvement rules if the addition value exceeds 50% of the principal structure's pre-improvement assessed value.
- wetland-overlay — Inside the Critical Area, the principal dwelling must have a minimum 600 sq ft gross floor area before an accessory apartment is permitted. Critical Area review runs concurrent with site-plan review; the Critical Area Commission may require additional buffer plantings or impervious-surface offsets.
- other — Pure interior conversions for accessory apartments rarely trigger FCA; new footprint or land disturbance may.
Known county issues (1)
- policy-review — Dorchester County must adopt a Chapter 155 amendment compliant with Maryland HB 1466 / SB 891 (2025 Accessory Dwelling Units Act) by 2026-10-01. Current Article XII Supplementary Use Regulations permit only interior accessory apartments capped at 800 sq ft or one-third of the principal dwelling; state law preempts a floor of detached ADUs sized up to 75% of the primary dwelling. Applicants should monitor county council agendas for the amendment and may invoke state preemption directly on or after 2025-10-01 if the county denies a compliant ADU on grounds inconsistent with the state floor.
Maryland state — ADU law and programs
State ADU law
Maryland enacted statewide ADU preemption with the Accessory Dwelling Units Act of 2025 — HB 1466 / SB 891 (cross-filed) — passed by the General Assembly in the 2025 Regular Session and effective 2025-10-01. Counties and municipalities with planning and zoning authority must adopt local laws compliant with the Act by 2026-10-01. The Act establishes that it is the policy of Maryland to promote and encourage ADU creation on land with a primary single-family detached dwelling. ADUs are defined as secondary units on the same lot/parcel/tract as a primary single-family detached dwelling, no greater than 75% of the size of the primary dwelling. Counties and municipalities cannot prohibit ADUs or impose unreasonable restrictions on their construction or rental. The 2025 ADU Act ALSO amends the Maryland HOA Act (Title 11B of the Real Property Article), prohibiting community associations from prohibiting or unreasonably restricting ADU construction and rental. The state has been preparing this framework since 2023 (SB 382 created the ADU Policy Task Force, which issued its final report 2024-05-31).
State HOA preemption
Maryland enacted HOA preemption for ADUs as part of the 2025 ADU Act. HB 1466 / SB 891 amended the Maryland Homeowners Association Act (Real Property Article, Title 11B), adding the ADU definition at §11B-101(a-1) and prohibiting HOAs from prohibiting or unreasonably restricting the construction or rental of ADUs on lots with primary single-family detached dwelling units. HOAs retain authority to (a) treat an ADU as a separate lot for voting and assessment purposes (optional, not required) and (b) impose reasonable design and architectural standards consistent with the community's overall character. The HOA preemption became effective 2025-10-01.
State financing programs
Maryland does not currently operate an ADU-specific statewide loan, grant, or forgivable-loan program tied to the 2025 ADU Act. The Maryland Department of Housing and Community Development (DHCD) administers a broad portfolio of homeownership, rental development, and home-repair financing — including the Maryland Mortgage Program, Settlement Downpayment Loan Program, Project Restore (commercial-to-residential conversions), and various Energy & Home Repair loan products. None target ADU construction directly, though Project Restore can fund ADU-like conversions, and the Energy & Home Repair Loan can fund ADU-related electrical, HVAC, and weatherization upgrades.
State housing programs
Maryland's primary state-level ADU program is the 2025 ADU Act framework: statewide preemption requiring local jurisdictions to adopt compliant ordinances by 2026-10-01, including HOA preemption. The Maryland Department of Planning maintains an ADU resource hub with technical assistance for local governments. Maryland does not currently operate a statewide pre-approved ADU plan catalog, an ADU rebate, or an impact-fee waiver statute, but the local-compliance window through 2026-10-01 is expected to produce additional ADU-specific incentive programs.
- ADU Act 2025 Statewide Floor (HB 1466 / SB 891) — Counties and municipalities with planning/zoning authority must adopt compliant ordinances by 2026-10-01, allowing ADUs on every single-family-detached lot at up to 75% of primary dwelling size. Bars prohibitions and unreasonable restrictions. Includes HOA preemption.
- Maryland Department of Planning ADU Resource Hub — Resource hub with model ordinances, FAQs for local governments (HB 1466 FAQ), task-force final report, and statewide ADU ordinance inventory.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.