Massachusetts Chapter 40A — Zoning Enabling Act (Framework) (MA)
Tracked preemption from the Massachusetts overlay bundle.
Overview
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Effective
1975-12-22
Sunset
—
Authority
state
Scope
state:MA
Trigger predicate
When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.
always true
Preempted fields
3 fields on the base district schema are rewritten when the trigger fires.
| Field | Op | Value | Note |
|---|---|---|---|
base_districts[*].nonconforming_use_protection | require | c40A_s6_protection | §6 protects pre-existing nonconforming structures/uses from zoning changes |
base_districts[category=res_sf].accessory_dwelling_unit | add | allowed_as_of_right | §3 (as amended by Affordable Homes Act 2024) requires ADUs to be allowed by right in single-family zones subject to reasonable standards |
base_districts[category=res].agricultural_use | require | permitted | §3 Dover Amendment — zoning cannot prohibit agriculture, religious, or educational uses |
Citation
Authority source
MGL c. 40A
§ c. 40A (Zoning Act); §3 (Dover Amendment, ADU mandate); §6 (nonconforming protection)
Research notes
Baseline statewide zoning enabling statute — structures every municipal zoning bylaw. §3 protects agricultural, religious, and educational uses from prohibition (Dover Amendment); 2024 Affordable Homes Act amended §3 to mandate as-of-right ADUs in single-family districts statewide. §6 protects nonconforming uses and structures. §9 governs special permits. §11 governs public hearing notice. Applies universally to all MA municipalities regardless of city-attribute values.