The Massachusetts Affordable Homes Act, signed by Governor Healey on August 6, 2024, aimed at addressing housing availability and affordability in the Commonwealth, includes certain changes to Massachusetts zoning law intended to promote increased housing development, such as office to residential conversion and as-of-right accessory dwelling units. One such change to G.L. c. 40A, § 6, addresses the common law doctrine of merger, a principle of zoning and planning established by courts in the Commonwealth for the purpose of minimizing zoning nonconformities.

Local zoning laws are widely regarded as essential components of city planning across the country, but are also sometimes criticized for disparate impacts on certain socioeconomic groups.

Pursuant to the Massachusetts Zoning Enabling Act, G.L. c. 40A, towns and cities in the Commonwealth adopt municipal zoning bylaws, which provide minimum requirements for lot size, frontage, setback, and other dimensions. However, many parcels of real property, already in existence at the time these zoning bylaws were enacted, may not conform to the new minimum requirements. These lawfully preexisting nonconforming lots are often afforded “preexisting nonconforming status” by municipal zoning bylaws so that they can be built upon or improved even if they do not meet current minimum zoning requirements. This preexisting nonconforming status does not only apply to lots that were rendered nonconforming at the time a city or town’s zoning ordinance was adopted; Massachusetts law also provides such status to single- and two-family residential use lots rendered nonconforming by changes to a municipality’s zoning bylaws if, prior to the increase in minimum requirements, the lot and building conformed to then-existing requirements.

Preexisting nonconforming status for legally preexisting lots ensures that parcels of real property already in existence at the time the zoning bylaws were adopted, or at the time changes to the zoning bylaws are enacted, are protected from depreciated property value as a result of their inability to conform to current minimum zoning requirements.¹ However, a competing fundamental purpose of zoning law is to promote the creation of conforming lots, and the law requires owners to minimize nonconformities wherever possible.

One way that the law requires owners of nonconforming lots to minimize zoning nonconformities is through the common law doctrine of merger, which provides that adjacent lots in common ownership will be treated as a single lot, for zoning purposes, to the extent necessary to reduce or eliminate the nonconformity. The merger doctrine is “automatic” when an undersized lot comes into common ownership with an adjacent lot. Generally, if a nonconforming parcel and an adjacent, conforming lot come into common ownership, those lots will be merged so that the entire lot is conforming. Generally, if two nonconforming lots come into common ownership, those lots will also be automatically merged even if the entire, merged parcel does not meet the zoning requirements, because reducing nonconformities is just as important as eliminating them. Also, once a nonconforming lot is owned in common with another parcel, those lots typically cannot be “de-merged” if a later conveyance reverts the lots into separate ownership. In such circumstance, even if the owner of a merged parcel does sell one or both lots to third parties, the nonconforming parcel normally will not be buildable because, at the time it was owned in common with the adjoining land, it lost its status as a lawfully preexisting nonconforming lot.

For adjacent lots to be subject to the merger doctrine, they must be owned in common, but common ownership is not limited to the name listed as the record title owner of each lot—the central inquiry is control. If two adjacent lots are nominally owned by separate persons or entities, but in actuality are in common control, Massachusetts courts will apply the merger doctrine. For example, in Murphy v. Board of Appeals of Billerica, 97 Mass. App. Ct. 901 (2020), the Massachusetts Appeals Court held that two lots held in common by spouses had merged, even though one lot was owned by the married couple and the adjacent lot was owned by two revocable trusts with the spouses as the respective trustees. Because the spouses were the sole trustees, settlors, and life beneficiaries of their respective trusts, with the power to revoke the trusts entirely, the spouses held complete control over both adjacent properties.

While the litmus test for “common ownership” is control, another probative factor is intent. If adjacent lots are owned by nominally different entities for the sole purpose of avoiding merger and preserving preexisting nonconforming status, it may tend to show that the lots remain in common control. For example, courts have rejected a practice known as “checkerboarding,” where an owner of several adjoining lots conveys individual lots to nominally separate entities in an alternating pattern to avoid merger. In DiStefano v. Town of Stoughton, 36 Mass. App. Ct. 642 (1994), the owner of a 40-lot tract of land tried to preserve preexisting nonconforming status by transferring ownership of some lots to himself individually, some to his wife, and some to himself as trustee of a realty trust, in an alternating pattern, but the Appeals Court found that all of the subject lots were still in common control.

Under the Affordable Homes Act, Massachusetts zoning law now includes a limited exemption to the doctrine of merger. According to a new provision in G.L. c. 40A, § 6, certain vacant lots held in common ownership with adjacent land “shall not be treated as a single lot for local zoning purposes” if certain requirements are met. The exemption applies if the commonly owned lot (1) is located within a single-family zoning district, (2) conformed with local zoning requirements at the time of its creation, and (3) contains at least 10,000 square feet of area and 75 feet of frontage. As a result of this exception to the merger doctrine, an undeveloped lot, owned in common with an adjacent lot at the time the local zoning ordinance rendered it nonconforming, will not be considered merged with the adjacent lot if it meets the three requirements listed above.

Section 6 also provides that, if the parcel meets these criteria, the new single-family house (i) cannot exceed 1,850 square feet of heated living area, (ii) must have at least three bedrooms, and (iii) cannot be used as a seasonal or short-term rental. These requirements for new construction on a nonconforming lot illustrate the merger exemption’s purpose in promoting the goals of housing affordability and availability. Additionally, the Affordable Homes Act includes certain provisions aimed to support first-time homebuyers; while the merger exemption in G.L. c. 40A, § 6 is not expressly directed at this demographic, some believe that the square footage limitation, three-bedroom minimum, and year-round home requirements appear to be primarily intended to promote the development of “starter homes” for first-time homebuyers.

Local zoning laws are widely regarded as essential components of city planning across the country, but are also sometimes criticized for disparate impacts on certain socioeconomic groups. The new provision in G.L. c. 40A, § 6 may be an attempt to strike a balance—it does not abolish the common law doctrine of merger, which serves to reduce or eliminate zoning nonconformities, but it does provide a limited exception for the construction of smaller, single-family, year-round residences, which is, at least, intended to promote an increase in housing availability.

¹Notably, each municipality’s zoning bylaws differ and provide protection subject to different conditions, so it is important to review your municipality’s specific requirements relative to protection of existing lots.