Anne Arundel County ADU Rules 2026: Size, Parking, Permits & Bill 61-26

Quick answer: Anne Arundel County currently allows one ADU on qualifying residential property. The County’s published rules allow interior, attached and detached ADUs; require no additional ADU parking; and currently cap a detached ADU at the lesser of 800 sq ft or 50% of the principal dwelling’s floor area. Bill 61-26 remains pending, so homeowners should verify the detached-size rule before paying for final plans. The county’s current public ADU guidance still reflects the Bill 6-23 framework, while pending Bill 61-26 proposes broader Article 18 changes after 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, or check the property address in the Maryland ADU Jurisdiction Finder first. For statewide context, use our Maryland County ADU Rules Tracker.

Source check, October 18, 2026: reviewed the Council bill record, linked amended bill PDF (printed page 145) and county ADU facts page. Proposed size changes remain separate from the county’s published current rules.This page is informational and is not legal, zoning, architectural, engineering, or permitting advice.

Anne Arundel ADU status at a glance

What the current Anne Arundel ADU rules say

Start with jurisdiction before design. An Anne Arundel mailing address does not by itself prove that County zoning controls the parcel. Properties inside Annapolis follow a different zoning authority, and Critical Area designation can materially change feasibility. Confirm the reviewing jurisdiction and Critical Area status before using the County detached-size rule as a design target.

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.

How the published detached-size formula works: 50% of a 1,200-sq-ft principal dwelling is 600 sq ft, below the 800-sq-ft cap. For a 2,000-sq-ft dwelling, the smaller figure is 800 sq ft. These examples explain the county’s published formula; they do not resolve the state/local size issue below or establish approval for a parcel. Record your measurements in the ADU size calculator.

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 linked bill PDF amended September 8, September 21 and October 5, 2026 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 was amended on September 8, September 21 and October 5, 2026 and remains pending. The County Council’s official record now schedules a hearing on the amended bill for October 19, 2026. Its ADU size provisions remain proposal-only; the cover dates do not establish when each individual provision was added.

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 linked proposed Bill 61-26 text amended September 8, September 21 and October 5, 2026 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. For sprinklers, one-hour separation, egress and conversion questions, use the Maryland ADU building-code guide.

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

1. Confirm the zoning district. The current public page excludes R22 and RCA land in the Chesapeake Bay Critical Area.
2. Identify the ADU form. Interior, attached and detached projects do not currently share the same size language.
3. 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.
4. Check accessory-structure setbacks. Detached ADUs use the district’s accessory-structure setback framework.
5. Check water/sewer or well/septic early. Private systems can materially change feasibility and schedule.
6. Verify short-term-rental rules separately. Do not assume ADU approval alone authorizes Airbnb-style use.
7. Track Bill 61-26. An amendment is not final law. Watch the October 19 hearing for posted amendment text, further changes, final passage, an enacted ordinance and an effective date.
8. Re-check before spending. Confirm the current rule with Zoning Administration before paying for final blueprints, a prefab deposit or site work.

Anne Arundel ADU questions before you apply

FAQ and preparation checklist added September 14, 2026. The county ADU facts page and Bill 61-26 schedule were rechecked for this section; the earlier review dates elsewhere on this page remain specific to those findings.

Does a garage conversion follow the attached or detached ADU rules?

Describe whether the garage is part of the house or a separate building when you contact Zoning Administration. The county publishes different size language for interior/attached and detached units, and says detached conversions must meet applicable construction-code requirements for new single-family dwellings. An existing garage is not automatically ready for residential use. See the official ADU facts and guidelines and our garage conversion planning guide.

Can I use Bill 61-26 to choose my ADU size now?

The official bill record checked October 18, 2026 lists amendments dated September 8, September 21 and October 5, with another hearing scheduled for October 19. It still shows no final passage, enacted ordinance or effective date. Ask which ordinance and measurement method apply to your proposed application; neither an amendment date nor a hearing date makes the proposal current law.

Will the ADU have its own address?

The county’s current ADU facts page describes a separate entrance and the same street address as the principal dwelling, designated Unit B. Confirm addressing details with the county before ordering signage or arranging services.

What should I gather before asking the county about my property?

This is a suggested preparation folder, not the county’s complete permit-submission checklist:

• Property identity: street address, parcel identifier and the zoning authority identified by the Jurisdiction Finder.
• Existing records: available survey or plat, building permits, floor plans and photographs of any structure proposed for conversion.
• Project outline: interior, attached or detached proposal; intended floor area; and a sketch showing the proposed location and distances to lot lines.
• Utilities and constraints: available water/sewer or well/septic records, easements and known environmental restrictions.
• Questions to resolve: accepted size measurement, applicable setbacks, required plans, review sequence and whether any pending ordinance affects the application date.

Ask Zoning Administration to identify the controlling code provisions and current submission instructions. Keep the dated response with your plans and record unanswered questions in the property feasibility checker.

Research changelog

October 18, 2026: rechecked the official bill record, amended PDF and county ADU guidance. The October 19 hearing remains listed without final passage or an effective date. Shortened repeated status notes and added examples of the published detached-size formula.

• October 10, 2026: verified that the linked proposed Bill 61-26 PDF now lists September 8, September 21 and October 5 amendments. Printed page 145 retains the detached-ADU 800-square-foot/50% limit and proposed 75% limit for other ADUs. The official record still lists an October 19 hearing, with no final passage or effective date shown. Updated the PDF descriptions; proposed provisions are not treated as current law.
• October 6, 2026: rechecked the official Bill 61-26 record, linked bill PDF and County ADU facts page. The record lists an October 5 amendment and October 19 hearing, with no final passage or effective date shown. The PDF is labeled September 8 & 21; October 5 amendment text is not identified in it. Retained the published detached-size rule and kept proposed changes separate.
• September 23, 2026: verified the County Council’s September 21 amendment entry and October 5 hearing date; confirmed no final passage, enacted ordinance or effective date is posted; retained the September 8 ADU wording as proposal-only because the linked bill PDF has not yet been updated to identify the September 21 changes.
• September 19, 2026: rechecked the County Council record; Bill 61-26 remains amended and pending, with the public hearing still scheduled for September 21 and no enacted ordinance or effective date shown.
• September 12, 2026: verified the County Council’s amended Bill 61-26 record and September 21 hearing date; retained Transition status because no enactment or effective date is shown.
• September 9, 2026: confirmed the bill remained pending after the September 8 hearing.
• September 6, 2026: published the initial comparison of current county guidance, Bill 61-26 and Maryland’s HB 1466 guidance.

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 — linked proposed text (amended September 8, September 21 and October 5, 2026)
• Maryland Department of Planning — HB 1466 FAQ
• Anne Arundel County — Residential Code Requirements

For statewide comparison, use the Maryland County ADU Rules Tracker, and for the full state-law framework see our Maryland ADU Guide 2026. Maryland ADU Guide is maintained by Gijo John as an independent research publication. Source-backed corrections can be sent to gijo.j@marylandaduguide.com.