ADU Pass
Charles County
ADU Pass helps homeowners in Charles County, Maryland navigate the permit paperwork for building an accessory dwelling unit. We cover 17 cities and 25 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Charles County (Southern Maryland; ~166,000 residents; seat at La Plata; bordered by the Potomac River to the south and southwest, the Patuxent River to the east, and Prince George's County to the north) regulates land use through the Charles County Zoning Ordinance (Subdivision 297, Article XII, Accessory Uses) and the Charles County Charter. Maryland is a home-rule state under Md. Const. Art. XI-A; Charles County is a charter county (charter adopted 2002, effective 2003) exercising broad self-governance, including zoning over all unincorporated land. The two incorporated municipalities, the Town of La Plata (~9,100) and the Town of Indian Head (~3,800), administer their own zoning under municipal charters. Maryland enacted the ADU Act of 2025 (HB 1466 / SB 891), which preempts local prohibitions and requires every county and municipality with planning/zoning authority to allow at least one ADU on every single-family-detached lot, capped at 75% of the primary dwelling. Charles County's pre-2025 accessory-dwelling provisions in Zoning Ordinance Article XII allowed accessory apartments by special exception in most residential zones; the County is presently amending the ordinance to comply with the 2026-10-01 statewide deadline. As of 2026-05-20, the Charles County Planning Commission has draft amendments under public hearing but no adopted ordinance update yet — HB 1466's by-right floor controls in the interim.
County assessor
Assessment policy: Maryland uses state-administered assessment under the State Department of Assessments and Taxation (SDAT). The SDAT Charles County Office assesses real property under Md. Tax-Property Code Title 8 on the statewide triennial reassessment cycle (Charles County is on Cycle 1, last reassessed for the 2026 tax year). New ADU construction is reassessed at full cash value as of the next reassessment cycle following completion; an Office of Information Technology in-field permit feed flags new construction for between-cycle assessments where the value change is material. Maryland's Homestead Tax Credit (Md. Tax-Property § 9-105) limits the homestead's annual taxable assessment growth; Charles County's homestead cap is 7% (set by Board of County Commissioners resolution, well above Maryland's lowest county-level caps). The state Senior Tax Credit (Md. Tax-Property § 9-258), Disabled Veteran Exemption, and Solar/Geothermal exemption may reduce property tax burden but do not change the assessed value of an ADU addition.
County overlays (5)
Known county issues (5)
- other — Charles County ADU applicants during 2026 face transitional rules: the by-right state floor applies but the County's local design standards (lot coverage, owner-occupancy, parking minima) are unsettled until adoption. Plan-review staff have indicated they will accept ADU applications on HB 1466 terms in the interim.
- other — ADU timelines on Critical Area parcels stretch 4-7 months for review; some RCA parcels along the Potomac and Patuxent shoreline cannot host new-construction ADUs at all.
- other — ADU projects in Pomfret, Pisgah, Hughesville, Bryantown, Nanjemoy, Welcome, Ironsides, and Issue face additional review time (typically 2-4 weeks beyond baseline) and design constraints to satisfy WCD standards.
- other — Parcels within 65+ dB DNL or impact-zone overlays around Indian Head require sound-attenuation construction; some 75+ dB zones restrict residential by-right and may prohibit new ADUs.
- other — Charles County ADU projects without family-member exemption incur ~$13,500 + excise tax (~$1.50/sqft) in county-collected charges before county permit fees, septic, and stormwater. The family-member exemption can save ~$13,500 but requires owner-occupancy by a qualifying relative.
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.