Please see our prior article for a full summary of the new amendments.

The Executive Office of Housing and Livable Communities (EOHLC) published draft ADU regulations on December 20, 2024, for a public comment period, to implement these amendments. The final regulations were published on January 31, 2025.

These regulations are now in effect and are codified in 760 CMR 71.00.

Within the regulations you will find definitions of the critical terms “Accessory Dwelling Unit”, “Protected Use ADU”, “Single-family Residential Zoning District”, and others. You also will find a list of “prohibited” regulations and “unreasonable” regulations which a municipality cannot impose.

Municipalities are required to keep a record of each ADU permit denied and approved and other data. The regulations span eight pages.

The EOHLC also is developing model ADU Zoning provisions for municipalities to use as a template if they choose to further “reasonably regulate” ADUs. For municipalities which already may have local ADU zoning provisions, the EOHLC will be publishing a checklist to help municipalities identify whether the current ADU provisions are compatible with the new state law and regulations.

With the new law in effect, we wait to see how municipalities, homeowners, builders, planners, architects, legal counsel and courts respond to it.

We are keeping track of emerging issues such as whether ADUs are allowed by right in any zoning district that allows single-family dwellings under any condition (including by special permit or variance); whether an ADU can have a different owner than of the principal dwelling unit; whether an ADU (meeting the legal requirements) can legalize an illegal or non-conforming existing unit; whether an ADU can be added to an existing commercial, industrial, or agricultural building where the zoning is residential (or residential is allowed); what else beyond the new regulations may be considered “unreasonable” regulation by a municipality; and what cities and towns may enact in their special permit standards for extra ADUs.

With this (some say) revolutionary change in Massachusetts real estate and land use law and our development landscape, some things are for sure

• You may now apply for a building permit for an ADU in every municipality; and
• Municipalities are busy revising their zoning bylaws and ordinances to add their mandatory ADU provisions.