Anne Arundel County already allows accessory dwelling units, but its 2026 zoning update creates an important transition problem for homeowners. The county’s current public ADU guidance still reflects the Bill 6-23 framework, while pending Bill 61-26 proposes broader Article 18 changes ahead of Maryland’s October 1, 2026 ADU compliance deadline.
The safest way to plan right now is to separate what is already in force from what Bill 61-26 proposes. This page does that explicitly and does not treat pending language as final law. If the property is inside Annapolis City limits, these County zoning rules do not control the ADU approval path; use our Annapolis ADU Rules 2026 guide instead. For statewide context, use our Maryland County ADU Rules Tracker.
Last verified: September 7, 2026. Bill 61-26 is pending and has a public hearing scheduled for September 8, 2026. This page is informational and is not legal, zoning, architectural, engineering, or permitting advice.
Anne Arundel ADU status at a glance
| Question | Verified status |
|---|---|
| Are ADUs currently allowed? | Yes. Anne Arundel County’s current public guidance allows ADUs under the Bill 6-23 framework. |
| Where are they allowed? | Residential zoning districts except R22, and not on land designated RCA in the Chesapeake Bay Critical Area. |
| Minimum lot size | No minimum lot size is listed on the county’s current ADU guidance. |
| Current detached size rule | Lesser of 800 sq ft or 50% of the floor area of the principal single-family detached dwelling. |
| Current parking rule | No additional parking is required for an ADU. |
| 2026 zoning update | Bill 61-26 is pending. Introduced July 20, 2026; public hearing scheduled September 8, 2026. |
| Is the detached-size issue settled? | No. The current county cap and pending bill language must be read alongside Maryland’s HB 1466 guidance. |
What the current Anne Arundel ADU rules say
The county’s current ADU facts page says an ADU may be located within, attached to, or detached from a single-family detached dwelling. A maximum of one ADU is allowed per lot.
For a detached ADU, the current page says the unit must be the lesser of 800 square feet or 50% of the floor area of the principal dwelling. An attached or interior ADU must be smaller than the principal single-family detached dwelling.
Detached ADUs use the accessory-structure setback standards for the zoning district. The county’s guidance also says side or rear setback variances generally may not be granted for an ADU, except for conversion of certain structures that existed before May 27, 2023.
Official current guidance: Anne Arundel County — ADU Facts & Guidelines.
What Bill 61-26 proposes
Bill 61-26 is a broad Article 18 zoning update introduced on July 20, 2026. It is not an ADU-only bill, but it contains proposed changes to the county’s ADU provisions and is part of the county’s larger 2026 zoning-code update.
The introduced bill keeps the existing rule that a detached ADU may not exceed the lesser of 800 square feet of floor area or 50% of the floor area of the principal single-family detached dwelling. For all other ADUs, the bill adds language stating they may not exceed 75% of the floor area of the principal dwelling.
Bill 61-26 is still pending. The County Council page lists a public hearing for September 8, 2026. Until final passage, amendments and an effective date are verified, homeowners should not design around the introduced bill as though it were enacted.
The detached-ADU size conflict: why we label Anne Arundel “Transition”
Maryland Department of Planning’s HB 1466 FAQ says local jurisdictions must authorize ADUs consistent with the state definition and may not limit ADU size below the 75% limit. The same FAQ says the state law does not prescribe one measurement method and recommends finished living area above grade for the primary dwelling.
Anne Arundel’s current public page, however, still publishes a detached cap of the lesser of 800 square feet or 50% of the principal dwelling’s floor area. The introduced Bill 61-26 keeps that detached cap while adding a 75% rule for other ADUs.
For a broader explanation of Maryland’s 75% rule and why measurement methods differ, use our Maryland ADU Size Calculator & Measurement Guide.
Parking and short-term rentals
Anne Arundel County’s current public ADU guidance says no additional parking is required for an ADU.
The same page says either the ADU or the principal single-family detached dwelling may be used as a short-term residential rental if either dwelling is owner-occupied, subject to the county’s separate short-term-rental rules. Homeowners should verify the current Article 11 requirements before relying on that use.
Permits, construction code and private utilities
A building permit is required to establish an ADU. Anne Arundel County says proposed detached ADUs—including conversions—must meet the applicable construction-code requirements for new single-family dwellings.
The county’s current guidance also says an ADU is exempt from impact fees if it is not constructed during construction of the principal single-family detached dwelling.
If the property is not connected to public water or sewer, treat Health Department review as an early feasibility issue. Anne Arundel County notes that private well/septic projects may require Health Department review and, depending on the site, perc testing. Use our Maryland ADU Septic & Well Readiness Guide before final design.
What Anne Arundel homeowners should do now
- Confirm the zoning district. The current public page excludes R22 and RCA land in the Chesapeake Bay Critical Area.
- Identify the ADU form. Interior, attached and detached projects do not currently share the same size language.
- Do not design a detached unit around one size assumption. The county’s current cap, Bill 61-26 and HB 1466 guidance are not yet fully reconciled.
- Check accessory-structure setbacks. Detached ADUs use the district’s accessory-structure setback framework.
- Check water/sewer or well/septic early. Private systems can materially change feasibility and schedule.
- Verify short-term-rental rules separately. Do not assume ADU approval alone authorizes Airbnb-style use.
- Track Bill 61-26. Look for amendments, final passage, an enacted ordinance and an effective date after the September hearings.
- Re-check before spending. Confirm the current rule with Zoning Administration before paying for final blueprints, a prefab deposit or site work.
Primary sources used for this Anne Arundel guide
- Anne Arundel County — Accessory Dwelling Unit Facts & Guidelines
- Anne Arundel County — Zoning Code Comprehensive Update
- Anne Arundel County Council — Bill 61-26
- Bill 61-26 — introduced text
- Maryland Department of Planning — HB 1466 FAQ
- Anne Arundel County — Residential Code Requirements
For statewide comparison, use the Maryland County ADU Rules Tracker. Maryland ADU Guide is maintained by Gijo John as an independent research publication. Source-backed corrections can be sent to gijo.j@marylandaduguide.com.