Zoning law explained
Massachusetts MBTA Communities Act Explained: What Section 3A Changes for a Site
What the MBTA Communities Act (Section 3A) requires of 177 Massachusetts cities and towns, the compliance deadlines, the 2025 and 2026 Supreme Judicial Court rulings, and what multifamily zoning as of right means for a developer.
The MBTA Communities Act is Section 3A of the Massachusetts Zoning Act. It requires each of the 177 cities and towns served by or next to the MBTA transit system to have at least one zoning district of reasonable size where multifamily housing is allowed as of right, at a minimum gross density of 15 units per acre. The law requires zoning, not construction. For a developer, it creates districts where an apartment project no longer needs a special permit.
What it is and how it works
Section 3A of Chapter 40A was signed into law in January 2021. The state housing office reproduces the text on its program page. It says an MBTA community must have a zoning ordinance or bylaw that provides for at least one district of reasonable size in which multifamily housing is permitted as of right. The statute sets these terms:
- The housing must be without age restrictions and suitable for families with children.
- The district must have a minimum gross density of 15 units per acre, subject to the state wetlands law and Title 5 septic rules.
- The district must be located not more than 0.5 miles from a commuter rail station, subway station, ferry terminal, or bus station, if applicable.
"As of right" is defined in the Zoning Act as development that can proceed without a special permit, variance, zoning amendment, waiver, or other discretionary zoning approval.
The Executive Office of Housing and Livable Communities (EOHLC) administers the law through regulations. They sort communities into four categories (rapid transit, commuter rail, adjacent, and adjacent small town) and set a minimum land area and unit capacity for each community's district. The program page has the regulations and each community's status.
Who and where it applies
The law applies to 177 MBTA communities. Boston is exempt from the Zoning Act, including Section 3A. Each community draws its own district, and the Attorney General's office describes cities and towns as having considerable discretion over its location and size. That means the law does not upzone every parcel near a station. It applies to the parcels inside the district lines each community chose.
Key dates
- January 2021: Section 3A signed into law.
- December 31, 2023: deadline for rapid transit communities.
- December 31, 2024: deadline for commuter rail and adjacent communities.
- January 8, 2025: the Supreme Judicial Court decided Attorney General v. Town of Milton. It held the law constitutional and enforceable by the Attorney General, and held that the state's implementing guidelines were ineffective because they had not been adopted under the Administrative Procedure Act.
- January 14, 2025: EOHLC filed emergency regulations. Communities that had missed earlier deadlines were given until July 14, 2025 to submit a district compliance application.
- December 31, 2025: deadline for adjacent small towns.
- January 29, 2026: the Attorney General sued nine towns for noncompliance: Dracut, East Bridgewater, Halifax, Holden, Marblehead, Middleton, Tewksbury, Wilmington, and Winthrop.
- September 18, 2026: in Marshfield v. Commonwealth, the Supreme Judicial Court affirmed the dismissal of a town's challenge. It rejected the claim that the law is an unfunded local mandate and concluded the act is a valid general law.
Current status
As of October 2026, the law has been upheld twice by the state's highest court. EOHLC's compliance sheet dated August 31, 2026 lists 157 of the 177 communities as compliant, 2 as conditionally compliant, 9 in interim compliance with applications under review, and 9 as noncompliant. That list changes as town meetings vote, so check the program page.
Do this in Plotzy
Ask the zoning code a question and get a cited answer
Zoning AI reads the ordinance for you. Ask about permitted uses, setbacks, FAR, height, or parking for a specific parcel and get the answer with the section it came from.
- Two-level zoning on every parcel, nationwide
- Plain-English answers with section-level citations
- Filter parcels by zoning before you spend a day on due diligence
7-day free trial
A community that does not comply is ineligible under the statute for certain state funds: the Housing Choice Initiative, the Local Capital Projects Fund, the MassWorks infrastructure program, and the HousingWorks infrastructure program. The Attorney General's January 2026 suit asks the court to order the named towns to adopt compliant zoning.
What this changes for a site
Inside a compliant district. Multifamily housing is a permitted use. A project that meets the district's dimensional standards does not need a special permit, variance, or zoning amendment for the use.
The 15 units per acre figure is a district minimum. It is a gross density the district as a whole must allow. It is not a guarantee for each parcel. The local bylaw sets the actual numbers lot by lot: units per acre or per lot, height, setbacks, lot coverage, and parking.
Which parcels are affected. Only parcels inside the adopted district. The base zoning shown on a town's map may not tell you whether a multifamily district or overlay applies, so check the adopted Section 3A district map.
What limits remain.
- Local dimensional and design standards written into the district.
- Wetlands and septic limits. The statute makes the minimum density subject to the wetlands law and Title 5, so those can limit unit counts on a site.
- Any local affordability requirement attached to the district.
- Developability. A district can meet the state's test and still contain little land that is practical to build on. Look at the parcels, not just the district boundary.
How to check a specific parcel
- Confirm the municipality is an MBTA community and check its compliance status on the EOHLC page.
- Find the adopted district map on the municipality's planning page, and confirm whether your parcel is inside it.
- Read the district's standards: density, height, setbacks, parking, and any affordability requirement.
- Check for wetlands and whether the site has sewer.
In Plotzy, filter parcels by zoning designation and lot size to list the lots inside a multifamily district, then ask Zoning AI "Is multifamily permitted as of right on this parcel, and what density applies?" for an answer with the code section cited.
Frequently asked questions
What is the MBTA Communities Act?
It is Section 3A of the Massachusetts Zoning Act, signed in January 2021. It requires 177 cities and towns to zone at least one district where multifamily housing is allowed as of right.
Does the MBTA Communities Act require towns to build housing?
No. It requires zoning that allows multifamily housing. Whether anything is built depends on owners and developers proposing projects on parcels in the district.
Is the MBTA Communities Act constitutional?
Yes, according to the Supreme Judicial Court. It upheld the law in Attorney General v. Town of Milton on January 8, 2025, and rejected a further challenge in Marshfield v. Commonwealth on September 18, 2026.
What happens to towns that do not comply?
They become ineligible for the state funding programs listed in the statute, and the Attorney General can sue to compel compliance.
Sources
The bills, statutes, court decisions, and agency documents cited on this page were checked on October 4, 2026. These laws have been amended and litigated since they passed, so confirm the current text and status before relying on any detail. This page is general information, not legal advice.
- Massachusetts Executive Office of Housing and Livable Communities: Multi-Family Zoning Requirement for MBTA Communities. Text of Section 3A, the 177 communities and Boston exemption, community categories, deadlines, funding consequences.
- Massachusetts Executive Office of Housing and Livable Communities: compliance status sheet as of August 31, 2026. Counts of compliant, conditional, interim, and noncompliant communities.
- Massachusetts Supreme Judicial Court: Attorney General v. Town of Milton, SJC-13580 (January 8, 2025). Holdings on constitutionality, enforcement, and the guidelines, and the statutory definition of "as of right".
- Massachusetts Executive Office of Housing and Livable Communities: emergency regulations press release (January 14, 2025). Filing date, the July 14, 2025 deadline, the December 31, 2025 deadline for adjacent small towns.
- Massachusetts Attorney General: press release on suit against nine communities (January 29, 2026). The nine towns, the relief sought, the January 2021 signing, local discretion over the district.
- Massachusetts Supreme Judicial Court: Marshfield v. Commonwealth, SJC-13840 (September 18, 2026). Decision date and holdings.
- Massachusetts Attorney General: statement on the Marshfield decision (September 18, 2026). Decision date and the claims the court rejected.
Related reading
- What Is Zoning Reform? A Plain Guide for Land Buyers and Developers
What zoning reform means, the main types (upzoning, missing middle housing, parking, ADUs, lot sizes, by-right approval), who is passing it, and what it changes for a specific site.
- What Is Upzoning? How It Works and What It Changes for a Site
What upzoning means, the three ways it happens (rezoning one site, citywide code changes, state mandates), real examples with numbers, and how to tell whether an upzoned parcel can actually carry more building.
- What Is Missing Middle Housing? Zoning Rules and What You Can Build
What missing middle housing means, which state and city laws now allow duplexes, triplexes, fourplexes, and townhouses on single-family lots, and what those laws let you build on a residential parcel.
- What Is R-3 Zoning? Low-to-Medium Density Multifamily Districts Explained
What R-3 zoning usually allows, the density, height, and parking rules that shape it, how Detroit, Phoenix, Los Angeles, and New York define it, and how developers use R-3 land.
- What Is R-4 Zoning? Medium-to-High Density Residential Districts Explained
What R-4 zoning usually allows, why it means mid-rise apartments in Los Angeles and detached houses in Baltimore, how New York, Anchorage, Phoenix, and Detroit define it, and what you can typically build.
- Multifamily Site Selection: Finding Land Zoned for Apartments by Right
Which districts allow multifamily by right, how density, height, and parking standards set your unit count, what recent state laws changed, and a parcel search recipe for apartment sites.