Can you build an ADU in Maryland in 2026? It depends on the county or municipality that controls the property. The October 1, 2026 state compliance deadline has passed. Current local rules and unresolved implementation questions vary by jurisdiction. Use the status labels below to separate active rules from pending proposals, then open the local guide before paying for plans or permits.
Not sure which local government controls your property? Start with the Maryland ADU Jurisdiction Finder. It checks the property address against Maryland government county and municipal boundary data before routing you to the correct rules path.
Tracker framework independently reviewed September 27, 2026. Each shared record below shows its own rule and authority review dates. We use county legislation, planning departments, zoning code materials and Maryland state guidance as primary sources. A status marked Transition means published rules, proposed changes or unresolved 2026 implementation need to be read separately. It does not establish that a replacement ordinance has been enacted. A status marked Legacy framework means older county rules are still published but a complete HB 1466 alignment measure has not yet been verified.
After identifying the controlling local rules, check property-specific constraints with our Maryland ADU septic & well guide and build a planning budget with the Maryland ADU cost calculator.
Compare key ADU rules by jurisdiction
Current-rule snapshot independently reviewed September 20, 2026. Proposed provisions are identified separately and are not treated as law.
On smaller screens, each jurisdiction appears as a readable card. On wider screens, scroll the table sideways to compare all columns.
| Jurisdiction & status | Size basis | Owner occupancy | Short-term rental | Parking | Approval path |
|---|---|---|---|---|---|
| Howard CountyACTIVE · SOURCE CONFLICT | County guidance uses up to 75% of the principal dwelling’s exterior footprint. | Required. The owner must live in the principal dwelling or ADU. | Prohibited. The enacted amendment covers compensated stays under 30 consecutive days. | Official sources conflict. The department summary describes three spaces; the legislative record retains one additional space and says the three-space amendment was not moved. Confirm with DPZ. | DPZ zoning approval, then applicable building/trade permits. A rental license may also be required when either dwelling is rented. |
| Montgomery CountyZTA 26-06 EFFECTIVE OCT. 5 · BILL 41-26 PENDING | Current general rule: ADU no larger than 75% of the primary single-family detached dwelling. A qualifying pre–May 31, 2012 detached-structure exception remains; confirm measurement and exception treatment with DPS. Overall lot coverage still applies. | Current Class 3 licensing includes owner-occupancy conditions. Bill 41-26’s proposed repeal remains pending. Confirm eligibility with DHCA for the planned rental arrangement. | An ADU is prohibited on a lot where a short-term residential rental exists or is licensed. | No extra ADU parking within one mile of Metrorail, Purple Line or MARC. Otherwise one ADU space in addition to any required main-dwelling parking, unless a Hearing Examiner waiver is approved. | Generally DHCA Class 3 licensing plus DPS permits; the qualifying pre–May 20, 2013 special-exception branch remains. Parking waivers and certain cases may involve OZAH. |
| Prince George’s CountyENACTED ZONING · NOT YET EFFECTIVE | CB-074-2026 was enacted September 29, 2026. The Council record lists November 16 as its effective date; the linked adopted text uses different commencement wording, so confirm the date with DPIE. CB-092-2026 remains pending. Do not treat the new zoning provisions as currently effective permit standards. Effective-date discrepancy and sources → | Not verified as a final local rule. | CB-092-2026 proposes a prohibition, but the proposal is not enacted law. | No final local ADU parking rule has been verified. | Ask DPIE and M-NCPPC to identify the rule and application path currently controlling the parcel. Municipal authority may differ. |
| Baltimore CountyLEGACY FRAMEWORK · TRANSITION | Interior/attached: lesser of one-third of dwelling floor area or 2,000 sq ft. Detached: 1,200 sq ft on at least one acre; 800 sq ft on a smaller lot. These are legacy limits, not a verified final HB 1466 framework. | Required under the current accessory-apartment definition. | No separate ADU short-term-rental rule was verified in the reviewed legacy provision. Confirm before planning rental use. | No new ADU-specific number was verified in §400.4; general site, access or hearing conditions may still apply. | Interior/attached: Use Permit. Detached: Special Hearing plus Use Permit. The current Use Permit is renewed every two years. |
| Anne Arundel CountyTRANSITION · BILL 61-26 PENDING | Current detached rule: lesser of 800 sq ft or 50% of principal-dwelling floor area. Attached/interior units must be smaller than the principal dwelling. The pending amended bill does not yet replace current law. | For the County’s published short-term-rental option, either the ADU or principal dwelling must be owner-occupied. Confirm any broader occupancy condition. | Current guidance allows either dwelling to be used as a short-term residential rental when either dwelling is owner-occupied, subject to separate Article 11 rules. | No additional ADU parking required under current County guidance. | A building permit is required. Detached ADUs, including conversions, must meet applicable new-single-family construction-code requirements. |
| Charles CountyENACTED · EFFECTIVE | Under 3 acres: lesser of 1,000 sq ft or 75% of principal-dwelling floor area. Three acres or more: up to 75%. | No controlling owner-occupancy condition was verified in the reviewed summary. Confirm with the Zoning Administrator. | No controlling short-term-rental condition was verified in the reviewed summary. Confirm before planning rental use. | No additional off-street space for the single-family-detached ADU use. Townhouse ADUs follow a different framework. | Zoning Administrator ADU determination, water/sewage approval, and applicable building/trade permits before occupancy. |
How to use this table: “Not verified” means we have not confirmed a controlling requirement in the reviewed official material; it does not mean the activity is unrestricted.
Open the linked jurisdiction guide for source citations, transition history and property-specific cautions. HOA covenants and assessment questions remain a separate statewide private-law check.
Maryland county ADU status at a glance
All 24 county-level jurisdictions plus a growing set of municipal profiles. Use the search to find the county or city research record. An unverified record means research is incomplete; it does not mean ADUs are prohibited.
No matching jurisdiction. Try a shorter name, or check which office reviews your property.
Allegany
Transition / Framework Conflict
Current County zoning separates residential accessory apartments from commercial/industrial accessory dwelling units. A final HB 1466-aligned countywide residential ADU framework has not yet been verified.
Anne Arundel
Transition
Existing guidance remains published. Bill 61-26 was amended October 5, 2026, and the official record schedules another hearing for October 19. It remains pending; no final passage, enacted ordinance or effective date is shown. Proposed changes are not current law. Legislative status checked: October 10, 2026.
Baltimore County
Legacy framework / Transition
Legacy accessory-apartment rules remain published; final HB 1466 alignment has not been verified.
Baltimore City
Transition
The September 24 committee record now has final minutes and records Bill 26-0195 as recommended favorably with amendment, Pass. The bill page remains In Committee with no enactment recorded. The October 8 hearing was rescheduled to October 22 at 9:00 AM.
Calvert
Enacted Active
Ordinance 41-25 updated the County ADU framework in 2025, including the 75% size standard and removal of the former primary-structure setback rule. Ordinance 22-26 added an ADU parking-waiver path in 2026. Owner occupancy remains required.
Last officially verified (independent source review): 2026-09-13.
Authority sources reviewed: 2026-09-13.
Caroline
Transition / Source Conflict
Caroline County currently allows ADUs under § 175-83, but the published 50% / 1,000-sq-ft size limits need to be reconciled with Maryland’s 75% HB 1466 standard before the October 1, 2026 compliance deadline.
Carroll
Adopted; exact effective date unresolved
Ordinance 2026-11: 75% size limits, three bedrooms maximum and no separate ADU parking requirement. The October 5 County reply confirms September 17 adoption but leaves September 17 versus September 27 as the exact effective date unresolved.
Cecil
Transition / Source Conflict
Cecil County still publishes an older accessory-apartment framework with 30% interior and 50%-of-accessory-structure size limits, while Maryland’s HB 1466 guidance says qualifying local ADUs may not be capped below 75% of the primary dwelling’s size. A replacement 2026 County ADU ordinance was not verified as enacted in this review.
Charles
Enacted Active
Bill 2026-06 was adopted July 7, 2026 and became effective August 21, 2026. The enacted framework allows one ADU per lot, including attached/interior and detached forms, with current size, water/sewage and permit standards.
Dorchester
Transition / Source Conflict
The live County code still defines an interior owner-occupied accessory apartment capped at the lesser of 800 sq ft or one-third of the building, with one extra parking space. Those limits need reconciliation with Maryland’s 75% ADU framework and parking-study/waiver requirements.
Frederick
Transition
An active ADU program remains in force. Bill 26-15 was introduced September 15, 2026, with a County Council public hearing scheduled for October 6, 2026; it remains proposed legislation.
Garrett
Transition · Jurisdiction-specific
Garrett County has no countywide zoning. Zoning applies in the Deep Creek Watershed and six incorporated towns, while unzoned areas follow a different permit path. No countywide HB 1466 ADU implementation ordinance was verified as of September 13, 2026.
Harford
Current rule: published legacy attached/interior family-housing framework.
Proposed/pending change: final 2026 local implementation and effective date not verified.
Last officially verified: 2026-09-12 (independent source review).
Page last reviewed: 2026-09-12.
Transition
Current family-only attached/interior ADU rules remain published while Maryland’s broader 2026 ADU requirements create detached-unit, size and parking alignment questions.
Howard
Source Conflict
CB 3-2026 is active, but official parking summaries and legislative records conflict.
Kent
Active framework · Parking verification
County Land Use Ordinance effective July 25, 2025 expressly permits one ADU in principal or accessory structures in listed County districts, requires owner occupancy, allows rental, and excludes ADUs from density. The current one-space rear-yard parking requirement should be confirmed against HB 1466’s parking-study and waiver requirements.
Montgomery
ZTA 26-06 effective; Bill 41-26 pending
Ordinance 20-36 (ZTA 26-06) was adopted September 15 and became effective October 5, 2026. It establishes the general 75% size rule, retains a qualifying older detached-structure exception and updates parking. Owner occupancy remains current; Bill 41-26 proposes separate licensing changes. Zoning and bill-status sources reviewed October 22, 2026. Licensing procedures and fees were not fully re-audited.
Prince George’s
Transition
CB-074-2026 was enacted September 29, 2026. The Council record lists November 16 as its effective date; the linked adopted text uses different commencement wording, so confirm the date with DPIE. CB-092-2026 remains pending. See the commencement discrepancy and confirm the application path.
Queen Anne’s
Transition
Current §18:1-48 allows one accessory guest residence/apartment up to 1,500 sq ft. Ordinance 26-15 proposes a by-right ADU framework for 2026. The September 21 Commissioners agenda placed the ordinance at the introduction / public-hearing-scheduling stage. It remains pending; no later adoption or effective date has been verified.
St. Mary’s
Transition / Source Conflict
The County still publishes legacy accessory-apartment rules with a 40%-or-900-sq-ft cap, owner occupancy and one additional parking space. Maryland HB 1466 requires a 75% size baseline and limits added parking rules. Final 2026 local alignment has not been verified.
Somerset
Transition / Source Conflict
Somerset County already permits several ADU forms, but its current ordinance caps ADUs at 50% of the principal dwelling’s living area and retains owner-occupancy and conditional parking rules. Maryland’s HB 1466 guidance says compliant local laws may not cap qualifying ADUs below 75%. No later County enactment resolving that conflict was verified as of September 13, 2026.
Talbot
Transition / Source Conflict
Talbot County currently allows interior and detached accessory dwellings, but its published 35%/900-sq-ft interior limit, fixed detached caps and one-space parking rule need reconciliation with Maryland’s HB 1466 size and parking requirements.
Washington
Enacted Active · Clarification Point
ORD-2025-33 was adopted and effective October 14, 2025. It permits one attached or detached ADU in specified County zoning districts, generally up to 75% of the primary dwelling’s GFA or 1,200 sq ft, whichever is less, with one additional parking space and a half-mile transit waiver. The separate 1,200-sq-ft cap should be checked against Maryland’s 75% rule on larger homes.
Wicomico
Enacted Transition / Source Conflict
Legislative Bill 2026-08 is enacted and scheduled to take effect October 19, 2026. The enrolled bill uses a 50% ADU size cap and one parking space per bedroom, creating implementation questions when read alongside Maryland HB 1466 guidance on the 75% size limit, parking studies and waiver procedures.
Worcester
Transition / Source Conflict
Worcester already allows accessory apartments, but current § ZS 1-338 still uses a 35% / 900-sq-ft maximum and requires one additional parking space. These published local limits need reconciliation with Maryland’s HB 1466 size and parking standards.
City of Takoma Park
Montgomery County zoning + City permit layer
Takoma Park does not administer separate ADU zoning. Montgomery County controls zoning/building review; the City adds municipality-letter, tree, stormwater, right-of-way, historic-district and rental-licensing requirements.
City of Annapolis
Transition
The City has an active ADU framework; final 2026 state-law alignment remains unresolved.
Town of Chesapeake Beach
Transition
The Planning & Zoning Commission held a second public hearing September 23 on revised zoning regulations that include draft ADU standards. No final recommendation or adoption has been verified; the draft provisions are not current law.
Town of North Beach
Transition / Source Conflict
The Town’s current accessory-apartment framework still uses a 5,000-sq-ft minimum lot, one off-street parking space, owner occupancy and an 800-sq-ft cap for a unit in an accessory structure. No newer enacted HB 1466-aligned ordinance was verified as of September 13, 2026.
City of Frederick
Transition
City zoning and permitting are separate from Frederick County; use the municipal carve-out guide.
Town of Walkersville
Transition
Town zoning and County permit routing remain a separate 2026 municipal pathway.
City of Rockville
Enacted Active
Rockville allows attached and detached ADUs under its own municipal zoning framework. Current guidance uses a 75% size rule, requires owner occupancy for at least six months of the year, and does not require ADU-specific parking.
City of Gaithersburg
Transition / Source Conflict
Gaithersburg administers its own zoning. Current Chapter 24 allows attached, integral and detached ADUs, but its 49% attached-size limit, 800/1,200-sq-ft detached limits, one-space parking rule and 10-foot detached setback need reconciliation with Maryland HB 1466.
City of Laurel
Ordinance 2057 adopted and effective September 28, 2026
Laurel administers its own zoning. Ordinance No. 2057 / Text Amendment No. 270 was adopted and approved September 28, 2026, and took effect on passage that day. Status checked October 10 against the signed ordinance. Confirm parcel-specific requirements with the City before design or permitting.
City of Aberdeen
Transition
Aberdeen adopted Ordinances 26-O-06, 26-O-07 and 26-O-08 on September 28, 2026. The package became effective October 19, 2026. Legislative status checked October 19 against the City adoption notices and legislation index. The Transition label identifies incomplete detailed-rule verification in this tracker. Confirm the rules for your property and filing date.
City of Havre de Grace
Transition
Current § 205-9H remains in effect. Ordinances 1229–1233 were introduced September 8, 2026, and the City held the advertised ADU public hearings on September 21. A subsequent enactment or effective date has not yet been verified, so the proposals are not treated here as current law.
Last officially verified: 2026-09-12.
Authority sources reviewed: 2026-09-12.
Authority, sources and research history
Zoning and permit intake: City of Havre de Grace Department of Planning.
- Havre de Grace ADU Rules 2026 guide
- Current City Code § 205-9H
- Official September 21 public-hearing notice
2026-09-12 — Dedicated guide added; pending ordinance figures remain separate from current rules.
Dated research background: The sections below preserve the September 9, 2026 research notes. Use the shared records above for current review status. Earlier descriptions and figures require confirmation before use on a property.
Howard County ADU rules — CB 3-2026
Howard County currently provides the clearest major-county example of a completed 2026 alignment. CB 3-2026 was signed in February and became effective April 8, 2026. The county allows attached and detached ADUs and renovation of existing space for an attached ADU in qualifying residential districts.
The county calculates maximum ADU size from the exterior footprint of the principal dwelling, with the ADU limited to 75% of that footprint. Howard County also requires the property owner to reside in either the principal dwelling or the ADU.
CB 3-2026 prohibits short-term rental use of ADUs. Parking requires extra care: Howard County’s current ADU webpage says parking was increased to three spaces with exceptions, but the final amended CB 3-2026 text still shows 1.0 additional off-street space per ADU, and the Council’s February 2, 2026 minutes state that Amendment 10—the proposed three-space change—was not moved. Because the county’s summary page and enacted-text record conflict, homeowners should confirm the currently enforced parking requirement with DPZ before filing. The county also applies lot-coverage and stormwater requirements to new detached ADUs. Read our complete Howard County ADU rules guide. Official Howard County ADU portal.
Montgomery County ADU rules — ZTA 26-06 effective October 5, 2026
October 22 source review: signed Ordinance 20-36 (ZTA 26-06) was adopted September 15, 2026 and became effective October 5, 2026. The County’s October 2026 DPS guidance reflects that effective zoning framework. Bill 41-26 is a separate pending licensing proposal.
The current general definition limits an attached or detached ADU to 75% of the size of the primary single-family detached dwelling. The ordinance removes the old attached 1,200-square-foot provision and detached smallest-of-10%-lot/50%-footprint/1,200-square-foot cap. Underlying-zone accessory-structure setbacks, height and building-lot coverage still apply. Confirm how DPS measures the primary dwelling and ADU for the 75% test before using a footprint or floor-area calculation.
Older detached structures have a retained exception: a structure legally constructed before May 31, 2012 may be used as a detached ADU without regard to setbacks or floor area if it is not increased in size or height and no new windows are added on the wall nearest an abutting property. Confirm eligibility and how DPS applies that exception alongside the new general definition; do not assume a universal 75% hard cap resolves every older-structure case.
Parking: no extra ADU parking is required within one mile of a Metrorail, Purple Line or MARC station. Outside that exemption, one on-site ADU space is required in addition to any required main-dwelling parking, unless the Hearing Examiner approves a waiver based on adequate on-street parking or a lot-size/shape impediment. If the main dwelling has no existing on-site parking, only the one required ADU space is needed. An ADU remains prohibited on a lot where a short-term residential rental exists or is licensed.
Owner occupancy remains current. Bill 41-26 is pending at Worksession as of October 23, 2026 (UTC). The October 21 staff report is for the scheduled October 26 PHP Committee worksession. No enactment or effective date is shown. As introduced, it proposes removing the rental-license owner-occupancy requirement and adding fee waivers for qualifying affordable ADUs. Those proposals are not current law. Generally, DHCA Class 3 licensing and DPS permits remain part of the process, with a retained branch for qualifying special exceptions approved before May 20, 2013. This October 22 review checked the signed zoning ordinance, DPS guidance and Bill status; it did not fully re-audit licensing procedures or fees. Read the Montgomery County ADU Rules guide and confirm the property’s applicable approval path.
Prince George’s County ADU rules — enacted zoning bill, not yet effective
Capitol Heights update: The Town considered a separate ADU proposal in 2026, but we have not verified that draft as adopted law. If your property is inside Capitol Heights, read the Capitol Heights ADU Rules 2026 guide before relying only on county-level information.
Checked October 8, 2026: CB-074-2026 was enacted September 29, 2026. The Council record lists November 16 as its effective date; the linked adopted text uses different commencement wording, so confirm the date with DPIE. CB-092-2026 remains pending. Read the enacted zoning bill separately from the pending non-zoning requirements.
The Council enacted the zoning bill on September 29, but the new framework is not yet effective. Read our Prince George’s County ADU guide. For municipality-specific layers, see Bowie, College Park, Greenbelt, Hyattsville, Mount Rainier, New Carrollton, District Heights, Cheverly, Laurel and Capitol Heights. Then check CB-074-2026 directly with the County Council.
Baltimore County ADU rules — legacy accessory-apartment framework
Baltimore County’s published zoning materials use the term accessory apartment. The legacy framework allows a second living quarter within a principal single-family detached dwelling or within an accessory building on the same owner-occupied lot, subject to detailed conditions.
Published legacy size limits include an internal accessory apartment of no more than one-third of the dwelling’s floor area or 2,000 square feet, whichever is less. For an accessory building, the older framework uses a maximum of 1,200 square feet on a lot of at least one acre and 800 square feet on a smaller lot. Detached units have historically required a Special Hearing and Use Permit.
Those legacy limits should not be assumed to be Baltimore County’s final HB 1466 framework. As of this review, the County Council’s current pending-legislation page did not show an ADU conforming bill that we could verify. We therefore label the county Legacy framework and will update this entry when a 2026 conforming measure is identified. Read our complete Baltimore County ADU transition guide, then check Baltimore County pending legislation.
Baltimore City ADU rules — Council Bill 26-0195 transition
October 8 research update: the September 24 committee record now has final minutes and records Bill 26-0195 as recommended favorably with amendment, Pass. That committee recommendation is not final enactment. The bill page remains In Committee with no final action or enactment number. Official September 24 meeting record.
Next scheduled hearing: the October 8 hearing was rescheduled to October 22, 2026 at 9:00 AM. The posted agenda includes Bill 26-0195. A scheduled hearing does not establish adoption or an effective date. Official October 22 meeting record.
Baltimore City is separate from Baltimore County. Council Bill 26-0195 was introduced May 11, 2026. The September 24 committee record now shows a favorable recommendation with amendment, Pass, while the bill page remains In Committee with no final enactment recorded. The October 8 hearing was rescheduled to October 22 at 9:00 AM. Proposed standards remain separate from currently effective law.
The first-reader text proposes a 75%-of-principal-dwelling-floor-area limit, specific ADU height rules and rear-yard/pervious-surface relief. Baltimore also already eliminated minimum off-street parking requirements citywide through Ordinance 25-064. The City requires extra care because ordinary rowhouse conversions are not automatically covered by Maryland’s single-family-detached HB 1466 mandate, while existing carriage-house rules and CHAP historic-district review create separate urban pathways. Read our Baltimore City ADU Rules 2026 deep dive.
Anne Arundel County ADU rules — Article 18 update
Anne Arundel County already allows ADUs under its 2023 framework. The county’s current public guidance says an ADU may be within, attached to or detached from a single-family detached dwelling, with no minimum lot size and no additional parking requirement.
The current public page still lists a detached ADU size of the lesser of 800 square feet or 50% of the principal dwelling’s floor area. Anne Arundel’s 2026 Article 18 draft adds a definition stating that an ADU may not exceed 75% of the floor area of the principal dwelling, but the same county draft says the stricter detached-ADU cap can remain. Maryland Department of Planning guidance says jurisdictions may not limit ADU size below the 75% limit. Because those official sources are not fully consistent, homeowners should treat the detached-size question as unresolved until final County Council action and legal interpretation. Bill 61-26 was amended September 8, September 21 and October 5, 2026. The County Council record checked October 10 schedules another hearing for October 19. The bill remains pending, with no final passage, enacted ordinance or effective date listed. The amendment schedule alone does not establish which ADU provisions will become law.
Because the current public ADU page and the pending 2026 update are not yet identical, this tracker labels Anne Arundel Transition. Read our Anne Arundel County ADU transition guide. Properties inside Annapolis City limits use a separate municipal zoning framework; see our Annapolis ADU Rules 2026 guide. Then review the official Article 18 update.
Frederick County ADU rules — active system, 2026 streamlining transition
Frederick County already has an active ADU program. ADUs not exceeding 1,000 square feet use the current permit pathway under §1-19-8.212, while larger ADUs require a Board of Appeals special exception under §1-19-8.321. Current rules also include owner occupancy, one additional parking space, annual owner reporting and a short-term-rental prohibition.
Frederick County Council later introduced Bill 26-15 — Accessory Dwelling Units on September 15, 2026. The measure remains proposed legislation, so the tracker keeps Frederick in Transition and does not treat the bill as current law. Frederick also has important private well/septic constraints, and its current larger-ADU size rules create a 50%-versus-state-75% alignment question. Read our Frederick County ADU Rules deep dive. Properties inside the City of Frederick or Walkersville follow separate municipal zoning paths; use our Frederick City vs. Walkersville municipal carve-out guide.
Carroll County ADU rules — current framework + 2026 transition
Adopted: Ordinance 2026-11. The signed text supplied by County staff establishes a shared §158.177 framework, including 75% floor-area and applicable footprint limits, a three-bedroom maximum and no separate ADU off-street parking requirement. September 27, 2026 remains the date previously confirmed by staff; the signed copy appears to show September 17. We have requested clarification. See the County guide before relying on older district-specific rules.
Use the Carroll County ADU Rules 2026 guide for the current size, parking, detached-unit and permit framework, including the adopted ordinance and effective-date clarification. Verify the parcel’s zoning district and current County interpretation before paying for design.
Aberdeen ADU rules — effective October 19, 2026
October 19 effective-date update: Aberdeen adopted Ordinances 26-O-06, 26-O-07 and 26-O-08 on September 28, 2026. All three became effective October 19, 2026. Legislative status checked October 19 against the City adoption notices and legislation index. Confirm the rules for your property and filing date. The September 14 packet linked below is historical; consult the final ordinances through the City legislation index. Official September 14 agenda packet · Official legislation status.
Legislative status: Effective October 19, 2026. Research status: Transition. Aberdeen administers its own planning, zoning and building-permit intake. Ordinances 26-O-06, 26-O-07 and 26-O-08 were adopted September 28 and became effective October 19, 2026. The Transition label reflects incomplete detailed-rule verification in this tracker. The effective date alone does not establish parcel-specific eligibility or permit approval. Confirm the applicable standards with the City for your property and filing date.
Use the Aberdeen MD ADU Rules 2026 guide if the property is inside Aberdeen. The City states that permits are applied for through Aberdeen, while Harford County DILP conducts building, plumbing, electrical and mechanical inspections after permit issuance.
Research record
How to read verification: A jurisdiction record is marked verified only when the cited official source was independently checked. That does not mean a government agency has approved a specific property or ADU project.
Status language: Enacted, Transition, Proposed, Legacy, and Source conflict are used to separate current rules from measures still moving through the legislative or implementation process.
Date language: A page update date is not automatically a new verification date. Where relevant, the tracker keeps the source verification date, webpage update date, and legal effective date separate.
How to use this tracker
- Do not treat a proposed ordinance as final. We distinguish proposals, committee actions and enacted law.
- Check your exact jurisdiction. Municipal zoning may differ from county rules. See our municipal carve-out research for Annapolis, Frederick City / Walkersville, and Chesapeake Beach.
- Verify before spending. Confirm the current ordinance with the local planning or permitting office before ordering plans, signing a prefab contract or paying a contractor deposit.
- Use the review date. Maryland is in an unusually fast regulatory transition through October 1, 2026.
Research methodology
For a source-linked county-level snapshot you can search or export, use the Maryland ADU 2026 County Framework Status Dataset. It shows the framework/transition status, verification date and primary official source for all 24 county-level jurisdictions.
This tracker is maintained by Gijo John for Maryland ADU Guide. We prioritize official county legislation, planning and zoning pages, staff reports, adopted code and Maryland state guidance. Third-party articles may help identify an issue to investigate, but they are not used as the final authority for a county status.
For the statewide baseline, see our Maryland ADU Guide 2026. Planning to reuse an existing garage? See Can I Convert My Garage Into an ADU in Maryland?. If parking could affect your project, use our Maryland ADU Parking Rules & Parking Study Tracker. If you need to know how close a detached ADU can sit to a property line, use the Maryland ADU Setback Rules lookup guide. For private-covenant questions, see Maryland ADU HOA Rules. Corrections supported by official sources can be sent to gijo.j@marylandaduguide.com.
Data & industry submissions
Maryland planning staff, architects, builders, permit professionals and manufacturers may submit a correction or field update. Include the jurisdiction, date observed, permit or case reference, and a direct official document or agency contact when available. Field reports help identify records to investigate; they are not published as law until independently verified against an official source.
Commercial relationships do not determine a jurisdiction’s status or source ranking.
What to do next
Start by finding the office that reviews your property. A mailing city or a county guide does not establish your parcel’s authority.
- Find Who Reviews My Property.
- Obtain your parcel identifier, survey, floor plans and utility records.
- Ask the reviewing office which current rules, supporting documents and approvals apply.
- Continue to your planning workspace.
Enable JavaScript to prepare a downloadable next-step brief. Planning guidance is not permit approval.