--- title: "In-Law Suites & ADUs in Anne Arundel County (2026) | TBG" description: "Can you build an in-law suite or ADU in Anne Arundel County? Zones, size limits, parking, septic and Critical Area rules, and the 2025 Maryland ADU law." url: https://thebrettgroup.com/guides/in-law-suites-adu-anne-arundel/ last_updated: 2026-10-13 --- [TBG](https://thebrettgroup.com/) / [Home Remodeling](https://thebrettgroup.com/remodeling/) / In-law suite guide Local guide · Anne Arundel County · October 2026 # In-law suites and accessory dwelling units in Anne Arundel County Anne Arundel County allows one accessory dwelling unit (ADU) on most single-family lots, inside the house, over a garage or in a separate building. The rules are being updated in fall 2026, so here is what applies now and what to confirm. Get matched with a builder who knows this - **1**: ADU allowed per lot - **800 sq ft**: Or half the house, whichever is less, for a detached ADU - **0**: Extra parking spaces required under the current county rules - **Oct 2026**: County update (Bill 61-26) under consideration **Updated October 13, 2026.** These rules are changing. A 2025 Maryland law requires counties to allow ADUs on single-family lots, and the county council is considering an update to its zoning code (Bill 61-26) this month. Confirm the current rules with the Office of Planning and Zoning (410-222-7460) before you design. ## 1. What the county allows today Since 2023 (Bill 6-23), an ADU is a **conditional use** in the RA, RLD, R1, R2, R5, R10 and R15 residential zones: it is allowed if it meets the conditions in the code. ADUs are **not allowed in R22** or in the Critical Area's Resource Conservation Area. There is no minimum lot size. One ADU is allowed per lot, and it can be inside the house, connected by a breezeway, in an attached or detached garage, or in a separate building; a mobile or manufactured home doesn't qualify. ## 2. Size and design A **detached** ADU can be no larger than **800 square feet or 50% of the main house**, whichever is less. An ADU inside or attached to the house must be smaller than the house. It needs its own entrance, shares the house's street address as "Unit B", and a detached unit follows accessory-structure setbacks. Setback variances aren't available, except to convert a building that existed before May 27, 2023. ## 3. Parking, fees and renting The county's current rules require **no extra parking space**, and ADUs are exempt from impact fees unless built together with a new house. Owner-occupancy is tied to short-term rentals: either unit may be rented short-term if the house or the ADU is owner-occupied. HOA covenants may still restrict ADUs, so check yours. ## 4. Septic and the Critical Area On a septic lot, the Health Department reviews the project: the system must be sized for the added living space and bedrooms, and the lot must have room for two future replacement systems. That is often the deciding factor; see our [septic guide](https://thebrettgroup.com/guides/septic-upgrades-bay-restoration-fund/). Near the water, an ADU adds lot coverage and must fit the [Critical Area limits](https://thebrettgroup.com/guides/building-near-the-water-critical-area/), and it is not allowed at all in the Resource Conservation Area. ## 5. What may change Maryland's 2025 ADU law (Chapter 196) requires local rules allowing ADUs on single-family land by October 1, 2026, with approval decisions within 90 days, objective standards, no new parking near transit and no impact fees for ADUs under 750 square feet. The county's pending Bill 61-26 would, among other changes, cap attached ADUs at 75% of the house and allow manufactured homes as ADUs. We will update this guide when the county acts. ## 6. Inside Annapolis The City of Annapolis has its own zoning rules for ADUs, including size limits, an owner-occupancy rule and a city rental license, and historic-district approval for exterior work. Check with the city's Planning and Zoning department. ## Where this comes up most [Crofton →](https://thebrettgroup.com/remodeling/crofton/) · [Odenton →](https://thebrettgroup.com/remodeling/odenton/) · [Glen Burnie →](https://thebrettgroup.com/remodeling/glen-burnie/) · [Severna Park →](https://thebrettgroup.com/remodeling/severna-park/) · [Millersville →](https://thebrettgroup.com/remodeling/millersville/) · [Linthicum →](https://thebrettgroup.com/remodeling/linthicum/) ## Projects we match - [Additions](https://thebrettgroup.com/remodeling/additions/anne-arundel/): Bump-outs, second stories and in-law suites. - [Basement finishing](https://thebrettgroup.com/remodeling/basement/anne-arundel/): Living space, egress, bathrooms and waterproofing. - [New custom homes](https://thebrettgroup.com/remodeling/custom-homes/anne-arundel/): Build on your lot with a registered Maryland home builder. ## Common questions ### Can I build an in-law suite in Anne Arundel County? In most single-family zones (RA, RLD, R1, R2, R5, R10 and R15), yes: one accessory dwelling unit per lot is a conditional use. ADUs are not allowed in R22 or the Critical Area Resource Conservation Area. Rules are being updated in fall 2026, so confirm with Planning and Zoning. ### How big can a detached ADU be? Under the current county rules, the lesser of 800 square feet or 50% of the main house's floor area. ### Do I need extra parking for an ADU? The county's current rules require no extra parking space. ### Can I put an ADU on a septic lot? Only if the Health Department approves the system for the added living space and bedrooms and the lot has room for two future replacement systems. ### Does Maryland require counties to allow ADUs? Yes. A 2025 law (Chapter 196) requires local rules allowing ADUs on single-family land by October 1, 2026. ## Official sources [AA County Bill 6-23](https://www.aacounty.org/county-council/legislation/bill-6-23) · [AA County ADU fact sheet (PDF)](https://www.aacounty.org/sites/default/files/2023-07/adu-fact-sheet.pdf) · [AA County Bill 61-26 (pending)](https://www.aacounty.org/sites/default/files/2026-07/bill-61-26.pdf) · [Maryland Chapter 196 of 2025 (SB 891)](https://mgaleg.maryland.gov/2025RS/chapters_noln/Ch_196_sb0891T.pdf) · [Maryland Dept. of Planning: ADUs](https://planning.maryland.gov/Pages/OurWork/PBP/ADUTF/ADU.aspx) · [AA County Health: permits on septic](https://www.aahealth.org/node/209) This guide is general information, not legal or engineering advice. Rules and maps change; confirm the requirements for your property with the permit office before you design or sign a contract. ## More local guides [Renovating or adding on in a flood zone in Anne Arundel County](https://thebrettgroup.com/guides/flood-zone-renovation-anne-arundel/) · [Building or adding on near the water: the Critical Area explained](https://thebrettgroup.com/guides/building-near-the-water-critical-area/) · [Remodeling ideas for Anne Arundel County's most common house types](https://thebrettgroup.com/guides/remodeling-anne-arundel-house-types/) · [Materials that hold up near the Chesapeake](https://thebrettgroup.com/guides/chesapeake-coastal-building-materials/) · [Septic upgrades and Bay Restoration Fund grants in Anne Arundel County](https://thebrettgroup.com/guides/septic-upgrades-bay-restoration-fund/) · [Deck permits in Anne Arundel County](https://thebrettgroup.com/guides/deck-permits-anne-arundel/) · [Energy rebates for Maryland home remodels in 2026](https://thebrettgroup.com/guides/energy-rebates-maryland-remodel/) · [Renovating a home in the Annapolis historic district](https://thebrettgroup.com/guides/annapolis-historic-district-renovation/) · [Do you need a permit to finish a basement in Anne Arundel County?](https://thebrettgroup.com/guides/basement-finishing-permit-anne-arundel/) · [Do you need a permit for a kitchen remodel in Anne Arundel County?](https://thebrettgroup.com/guides/kitchen-remodel-permit-anne-arundel/) · [Do you need a permit for a bathroom remodel in Anne Arundel County?](https://thebrettgroup.com/guides/bathroom-remodel-permit-anne-arundel/) · [Do you need a permit for a fence in Anne Arundel County?](https://thebrettgroup.com/guides/fence-permit-anne-arundel/) · [Do you need a permit for a shed or detached garage in Anne Arundel County?](https://thebrettgroup.com/guides/shed-permit-anne-arundel/) · [Remodeling permits in Anne Arundel County and Annapolis](https://thebrettgroup.com/guides/permits-anne-arundel-annapolis/) · [How to hire a home improvement contractor in Maryland](https://thebrettgroup.com/guides/hiring-a-contractor-maryland/)