Do I Need Extra Parking for an ADU in Maryland? 2026 County-by-County Rules

Sometimes—but Maryland no longer lets a local government add extra ADU parking requirements without first doing the homework. Under Land Use §4-504(e), a county or municipality that wants additional off-street parking for an accessory dwelling unit must first complete a parking study, consider four specific factors, and include a waiver process in the local law.

Quick answer

Your ADU may need extra parking—but the local rule should be traceable to a study and waiver process.

A missing study does not automatically prove a parking rule is invalid, and a jurisdiction that requires no additional ADU parking does not need to conduct the HB 1466 parking study. This tracker records what we can actually locate in official sources.

Last verified: September 8, 2026. Maryland jurisdictions are still finalizing local ADU laws before the October 1, 2026 deadline. We label a parking study “located” only when we can point to an official study or official local record. “Not located” means exactly that—it is not a finding of legal noncompliance.

1. Maryland’s ADU parking rule: what HB 1466 actually requires

Maryland Land Use §4-504(e) does not ban local ADU parking requirements. It allows a local law to establish additional off-street parking, but the law must consider four factors:

Construction cost: the cost to create off-street parking spaces.
Curb availability: whether enough curb area exists along the property frontage to accommodate on-street parking.
Impervious surface: the added paved area and its relationship to stormwater management.
Lot-size variability: how parking feasibility changes with the size of the lot, parcel or tract.

The local law must also provide a waiver process. Most importantly, before adopting an additional ADU off-street parking law, the legislative body must complete a parking study to determine the applicable parking needs and restrictions in that jurisdiction.

Maryland does not define a universal study format. The Maryland Department of Planning says HB 1466 does not define the elements of a parking study, but it does require additional ADU parking rules to consider the four factors above and include a waiver process. That is why this tracker records the evidence instead of declaring a study “legally valid” or “invalid.”

If a jurisdiction requires no additional off-street parking specifically for the ADU, Maryland Department of Planning says the jurisdiction does not need to complete this study. For the statewide legal baseline beyond parking, see the Maryland ADU Guide 2026.

2. Maryland ADU parking study tracker

Jurisdiction	Extra ADU parking?	Study located?	Waiver found?	Research status
Montgomery County	Yes — current/proposed framework generally uses 1 ADU space, with transit relief	✅ Yes — formal 2026 ADU Parking Study	✅ Yes — Hearing Examiner process	Best documented example
Anne Arundel County	No additional parking under current ADU guidance	N/A	N/A	Clear current rule
Chesapeake Beach	Existing/draft framework has been under review	🟠 Study process documented; completed study not yet located by us	Waiver language has been discussed/recommended	Transition
Walkersville	Planning Commission discussed a possible ADU parking rule	🟠 Study required before rule; completed study not yet located by us	Not established in the April minutes reviewed	Transition
Howard County	⚠️ Official sources conflict over the 1-space vs. 3-space amendment history	ADU-specific study not yet located by us	Exception language appears in Amendment 10	Source reconciliation required
Prince George’s County	2026 ADU legislation remains pending	Not located in materials reviewed	Not yet verified	Transition
Baltimore County	Legacy accessory-apartment framework remains published	2026 HB 1466 study not verified	Not verified	Legacy / research pending

How to read the table: a blank or unverified study is not the same thing as a legal defect. A jurisdiction may still be drafting its local law, may ultimately remove extra ADU parking, or may have a study that has not yet been surfaced in the official materials we reviewed.

3. Montgomery County: the clearest HB 1466 parking-study example

Montgomery County provides the strongest primary-source example we found. Its ZTA 26-06 legislative packet includes a document titled Accessory Dwelling Unit Parking Study and expressly says the document serves as the parking study necessary for HB 1466 compliance.

The study also says no formal parking study was performed when Montgomery’s 2019 ADU parking rules were adopted. For the 2026 update, Planning Staff analyzed all four state factors and recommended keeping a baseline of one parking space per ADU, keeping the one-mile transit exemption, removing a rule that could force two new spaces where no driveway exists, and retaining/expanding the waiver process.

HB 1466 factor	What Montgomery’s study addresses
Cost	Uses an estimated 175 sq. ft. parking-space expansion and estimates the added concrete cost at just under $3,000, while noting site costs vary.
Curb space	Discusses case-by-case street conditions, hydrants, utilities, driveway spacing, street width and topography.
Impervious surface	Analyzes the added paved area and drainage/stormwater implications.
Lot-size variability	Uses county lot-size distribution and explains why lot shape, size and topography change parking feasibility.
Waiver	Retains the Hearing Examiner waiver for adequate on-street parking and recommends an additional waiver where lot size or shape effectively prevents the extra space.

Montgomery is still a transition jurisdiction under ZTA 26-06, so the study should not be confused with a final enacted 2026 ordinance. But as a research model, it shows exactly what homeowners should look for when a local government wants to preserve an additional parking requirement. Read our Montgomery County ADU transition guide.

4. Howard County: a real official-source conflict on ADU parking

Howard County is the reason this tracker does not simply copy a planning webpage. The County’s current ADU page says CB3-2026 increased off-street parking per ADU from one space to three spaces, with exceptions.

But the February 2, 2026 County Council session minutes state that Councilmember Yungmann did not move Amendment 10. Amendment 10 was the proposal that would have changed the parking table from 1.0 to 3.0 spaces and added an exception based on available on-street parking.

Complicating the record further, an official Amendment 10 document now carries certification text saying it was “passed on Feb 2, 2026.” In other words, the public-facing county page, the session minutes and the amendment document do not line up cleanly.

Tracker status: source conflict. We are not publishing a definitive Howard County parking number from these conflicting records. We also have not yet located an ADU-specific HB 1466 parking study in the official materials reviewed. Homeowners should confirm the currently codified and enforced parking rule directly with Howard DPZ before designing a site plan.

This is exactly why Maryland ADU Guide separates what a summary page says from what the legislative record says. See the Howard County ADU guide.

5. Anne Arundel County: no extra ADU parking, so no HB 1466 study trigger

Anne Arundel County’s current ADU facts page says simply: no additional parking is required for an ADU.

That distinction matters. Maryland Department of Planning says a jurisdiction only needs the HB 1466 parking study if its local law imposes an off-street parking requirement on ADUs. A jurisdiction that requires no additional ADU parking does not need to perform the study just to comply with the parking subsection.

So Anne Arundel should be marked N/A, not “study missing.” Its broader ADU rules remain in transition under Bill 61-26. Read our Anne Arundel County guide.

6. Chesapeake Beach: a town openly working through the parking-study requirement

Chesapeake Beach gives us a useful municipal example. Town planning materials explain the HB 1466 requirement in plain language: the Town may not require ADU parking without first conducting a parking study, and a waiver process must exist if parking requirements remain.

An April/May draft still showed the Town’s existing rule of two additional off-street parking spaces for an ADU, while the Town’s own explanatory document said it would either need to remove that parking requirement or complete a parking study. June Council minutes then record a lengthy discussion about ADU parking and the need for a town parking study, with a waiver provision being recommended so the law could move toward the October deadline.

Why this matters: Chesapeake Beach shows the statute working exactly as intended as a procedural guardrail. The Town identified an existing parking mandate and then had to decide whether to remove it or build the study-and-waiver record needed to retain additional ADU parking.

As of this September 8 review, we found official records documenting the study process, but we have not yet located a final completed parking-study document that we can label “Study verified.” The Town’s current code also contains a parking-source conflict between §290-11 and the parking table; see our Chesapeake Beach ADU Rules 2026 deep dive for the full source comparison.

7. Walkersville: the Planning Commission explicitly paused parking rules until a study

Walkersville’s April 14, 2026 Planning Commission minutes are unusually direct. When members discussed whether to limit parking to one vehicle per ADU, the Planning and Zoning Administrator said the State’s direction was that the parking study had to come first.

The minutes also state that no waiver process had yet been established and that the Town would need to create one. Later in the discussion, staff again said that no ADU parking requirement could be established until the required study was conducted.

Walkersville’s official Town Code page currently lists Draft Ordinance No. 2026-04 — Accessory Dwelling Units. We therefore classify Walkersville as a transition jurisdiction: the study requirement is clearly recognized, but a final study/parking rule should not be inferred from the April discussion alone.

8. Prince George’s and Baltimore County: what we can responsibly say today

Prince George’s County

CB-074-2026 was presented and referred on July 7 and appeared before the PHED Committee on September 3. The official committee page still does not provide a finalized action record for that meeting. In the official material reviewed for this tracker, we have not yet located a completed HB 1466 parking study or a final enacted ADU parking rule. That is why Prince George’s remains Transition / study not located, not “noncompliant.” Track Prince George’s County here.

Baltimore County

Baltimore County still publishes its older accessory-apartment framework under §400.4. That legacy material is useful for understanding the current permit structure, but it is not enough to tell us what the County’s final HB 1466 parking policy will be. We have not yet verified a 2026 ADU parking study tied to a final conforming ordinance. See the Baltimore County transition guide.

9. If your county says you need extra ADU parking, ask these five questions

What exact code section requires the extra ADU parking? Ask for the enacted section, not a brochure summary.
What parking study did the legislative body complete before adopting that rule? Ask for the study title, date and official link.
Where does the study address cost, curb space, impervious surface/stormwater and lot-size variability? These are the four factors named in §4-504(e).
Where is the parking waiver process? Ask who decides it, what evidence is required, and whether on-street parking or lot constraints can support a waiver.
Is this ADU-specific parking or replacement parking for the main house? Garage conversions in particular can create a separate question about replacing parking that served the principal dwelling.

Useful written question: “Please identify the currently enforced ADU off-street parking requirement for this property, the parking study completed before that requirement was adopted, and the published waiver process required under Maryland Land Use §4-504(e).”

If you are still determining whether the property can support an ADU at all, start with the Maryland ADU Property Feasibility Checker. If you are converting a garage and may lose existing parking, see Can I Convert My Garage Into an ADU in Maryland?.

10. Bottom line

Maryland does not guarantee every ADU will be parking-free. What HB 1466 changes is the process: a jurisdiction that wants additional ADU off-street parking has to build a record first, consider the specified homeowner/site impacts, and provide a way to seek a waiver.

For homeowners, the practical question is no longer just “How many parking spaces does my county require?” It is also: “What study supports that requirement, and where is my waiver path?”

Because local legislation is moving quickly through October 1, use the Maryland County ADU Rules Tracker alongside this page and verify the linked primary source before relying on a parking requirement.

Primary sources used for this parking tracker

Maryland ADU Guide is maintained by Gijo John as an independent research publication. We prioritize enacted law, legislative records, local planning documents and official government guidance. This page is informational and is not legal or permitting advice. Source-backed corrections can be sent to gijo.j@marylandaduguide.com.