Understanding Zoning Rules for Massachusetts 40B Affordable Housing

Office Building

Affordable housing has become an increasingly pressing issue in Massachusetts, with high housing costs and limited availability making it difficult for many residents to find a home they can afford. In response, the state has implemented a number of policies designed to promote the development of affordable housing, including the 40B program.

The 40B program is a state law that allows developers to bypass certain zoning rules in order to build affordable housing. In this article, we’ll take a closer look at how the program works and what it means for both developers and residents.

What is the 40B Program?

The 40B program, also known as Chapter 40B or the Comprehensive Permit Law, was created in 1969 with the goal of promoting the development of affordable housing in Massachusetts. Under the law, developers can apply for a comprehensive permit that allows them to bypass certain zoning regulations if they agree to set aside at least 25% of their units as affordable.

This means that developers can build multi-family housing in areas where it would not normally be allowed under local zoning laws. For example, if a town’s zoning bylaws only allow single-family homes on large lots, a developer could apply for a comprehensive permit to build an apartment complex on a smaller lot.

How Does It Work?

To apply for a comprehensive permit under the 40B program, developers must submit their plans to both the local zoning board and the state Department of Housing and Community Development (DHCD). The DHCD reviews each application to ensure that it meets certain eligibility criteria before issuing a “project eligibility letter.”

Once a project has received its eligibility letter, it moves forward into what’s known as the “comprehensive permitting” process. During this process, the local zoning board holds public hearings and works with the developer to address any concerns raised by community members.

If everything goes smoothly during this process, the project will be granted its comprehensive permit. This allows developers to bypass certain local zoning regulations in order to build their affordable housing project.

What Are Some Benefits of 40B?

There are several benefits associated with the 40B program:

Increased Availability of Affordable Housing

One of the main goals of the 40B program is to increase access to affordable housing for low- and moderate-income families. By allowing developers to bypass certain zoning regulations, more multi-family housing units can be built in areas where they might not otherwise be allowed.

More Diverse Communities

Because multi-family developments are often located near transit hubs or other amenities like shopping centers or schools, they can help create more diverse communities by providing access to these resources for people who might not otherwise have them.

Economic Benefits

Developers who participate in the 40B program may be eligible for tax credits or other financial incentives from both state and federal governments. Additionally, because multi-family developments tend to be more efficient than single-family homes when it comes to things like energy usage and infrastructure costs (like roads), they can help reduce overall costs associated with development.

What Are Some Concerns About 40B?

While there are certainly benefits associated with Massachusetts’ 40B program, there are also some concerns:

Local Control

Some people worry that allowing developers to bypass certain local zoning regulations undermines local control over land use decisions. Because these decisions are made at both the municipal and state levels (with DHCD oversight), some feel that communities don’t have enough say over what gets built where.

Potential Negative Impacts on Neighborhoods

In some cases, multi-family developments built under Chapter 40B may have negative impacts on existing neighborhoods. For example, increased traffic congestion or parking shortages could make life more difficult for nearby residents.

Limited Number of Units Set Aside as Affordable

While requiring developers who participate in Chapter 40B programs set aside at least 25% of their units as affordable is certainly better than nothing when it comes to increasing access to affordable housing – some argue that this isn’t enough.


Massachusetts’ Chapter 40B law has been helping promote affordable housing development across the state since its creation over fifty years ago. While there are certainly pros and cons associated with any policy decision – overall – many believe that this law has helped increase access to much-needed affordable housing while also creating more diverse communities throughout Massachusetts.