Who Actually Owns the ADU on My Property, and Why That Matters More Than You Think

By Buz Artiano, BuildX | June 2026

Watch: 40% of Caregivers Pass First: Here's Why That Matters for Your Family

You're about to invest $300,000 or more into building an ADU on your property, and you assume the person living there will have some kind of ownership, but that's actually not the case. Most families building an ADU for aging parents, adult children, or family members with disabilities never ask the ownership question until they've already spent the money. But by then it can get legally very complicated. The ADU belongs to whoever owns the property. The person living in it doesn't own any part of it unless you take specific legal steps before you start building.

My name is Buz Artiano, and I started BuildX. Since then we've built dozens of ADUs all over Massachusetts, but most of our builds have been around the South Shore and Plymouth County areas. We handle all the design, permitting, and construction ourselves and we deal with zoning, septic constraints, and the state's ADU regulations every day. I can tell you from experience that talking about the ownership structure of the ADU is one of the most important legal conversations you need to have before you spend any money on construction.

In this article we'll talk about and explain exactly who owns an ADU under Massachusetts law, why that matters for estate planning and family protection, and what you need to do to make sure the person living in your ADU is covered. We work alongside estate planning attorneys on every project because the building is only the building. The legal structure around it is what protects your family.

Does the Person Living in My ADU Actually Own It?

No. Under Massachusetts property law, an ADU isn't owned independently. As estate planning attorney Erin Nunes of Supernot, Boneski & Nunes explains from her 21 years of practice, the ADU is part of the property. The person living in it does not own the ADU.

That means if your parents sell their house for $1 million, invest $400,000 of that money into building an ADU on your property, and move in, they still don't own any part of that ADU even though they paid for it. You, the property owner, have had your property's value increased by $400,000. Your parents have spent $400,000 and own nothing.

That's not necessarily a problem, it's just that that is the legal default unless you take the steps to change it. Most people don't think to ask about this, and that's why we bring it up with every client because we've unfortunately seen what happens when families skip this step and then face a divorce, a health crisis, or a death without a plan in place.

Why Does ADU Ownership Structure Matter Before Construction?

The ownership question is not insignificant. It has an effect on all the decisions your family will make down the line, from estate distribution to MassHealth eligibility to what happens if the property owner gets divorced.

Consider a family with three adult children: Mary, Jane, and Sally. The parents choose to build an ADU on Mary's property because she has the land. Jane lives in a condo, and Sally is renting a place. The parents invest $400,000 from the sale of their home to build the ADU. As a result, Mary's property value increases by $400,000. When the parents pass away, the rest of their estate is divided up. Jane and Sally look at the numbers and realize Mary got $400,000 in property value when they got nothing. Without proper estate planning, this situation can cause huge family conflicts.

At BuildX, we tell every family that building an ADU is 70 percent family dynamics and only 30 percent construction. Attorney Nunes actually says it's more like 80/20. In our experience, around 30 percent of ADU projects that start with a deposit conversation are never able to get to the construction phase because families can't resolve the legal and emotional side of things. The ownership question is where most of those conversations break down.

What Are My Options for Protecting the Person Living in the ADU?

There are several things that families can do to protect whoever lives in the ADU. The right method depends on your family's goals, financial situation, and long-term care needs. Here are the most common ways to set it up:

Life estate or right of occupancy. This gives the ADU occupant a legally protected right to live in the ADU for the rest of their life, regardless of what happens to the property. Even if the property is sold, the buyer is legally required to allow them to stay living there forever. This is especially important when parents are getting older and trying to move them would be extremely difficult or unsafe.

Trust with specific provisions. All parties, including the property owner and their spouse, can create a trust that says what happens to the ADU investment for all kinds of different scenarios like divorce, sale, death, or long-term care needs. The trust can say that the investment has to be given back if the property is sold. It can also outline a specific amount of time that the people living in the ADU have to move out if circumstances change.

Deed placement (with caution). Parents can be added to the property deed, making them part owner. If the property is worth $800,000 after the ADU is built and the parents put in $400,000, they would own about 50 percent. Doing it this way technically makes it a purchase and not a gift, which has a big effect when it comes to MassHealth eligibility. But there are risks. If both parents die before the property owner, the property could then be susceptible to a MassHealth lien. Attorney Nunes advises that you do not just run out and put mom and dad on your deed because you are building an ADU.

Contractual provisions. Even without deed changes or trusts, written agreements between family members can give you some protection. Things like repayment obligations if the property is sold, pre-determined amounts of time to move out, and terms on how to get your investment back. These agreements should always be officially drawn up by an attorney.

We talk about all these things with every family before we quote a project for them. At the end of the day, if you talk to an estate planning attorney before construction begins you are much more likely to get to your move-in day without having to deal with expensive and time consuming legal complications. But the families who skip this step represent about 30 percent of projects that simply never get built. We've learned to make the legal conversation part of the building conversation because they have to go hand in hand.

What Happens If the Property Owner Gets Divorced?

This scenario catches a lot of people off guard. Let's say the parents have invested $400,000 to build an ADU on Mary's property, but then Mary gets divorced. The property is considered a marital asset. Attorney Nunes says that without legal protections in place, the parents could be in serious trouble.

The parents' health has likely changed with age since they moved in, which means relocating is not a simple task. The $400,000 they invested is now tied up in a property that is being divided in a divorce proceeding that they are left out of entirely.

If you do the right legal planning before starting construction, you can prevent this. A trust with divorce provisions, a recorded life estate, or a contractual agreement between all parties, including the spouse, can establish that the parents keep their right to live there and their financial investment through the divorce. The most important thing to remember is that the paperwork has to be in place before construction starts. Once the ADU is built and the money is spent, your leverage to negotiate protections is gone.

Can MassHealth Come After My Parents' ADU Investment?

If your parents invest $400,000 in an ADU and later need nursing home care, that investment could be classified as a gift under current Medicaid rules. MassHealth has the right to look back into financial records for five years. If the ADU was built in that time, Medicaid could see it as a gift and that could trigger a penalty period where you aren't eligible for coverage.

There is a legal exception though. Medicaid is not supposed to penalize you if the transfer was not an attempt to spend down your assets so you can qualify for benefits. Attorney Nunes has had success making this argument in other cases. That being said, the further back in time the transfer occurred, and the more cash the parents retain, the stronger the case. However, she is clear that this argument has not yet been tested specifically in the context of an ADU investment.

Adding the parents to the title can help though. If the parents go on the deed and their $400,000 investment shows a 50 percent share in an $800,000 property, the transfer is a purchase, not a gift because they are just buying equity. That can mean the difference between MassHealth eligibility and a penalty period where you are responsible for all your own health care costs. You can review the current MassHealth eligibility framework at mass.gov.

Nunes says that the goal of pre-construction legal planning is to stave off Medicaid for as long as possible, not to qualify for it. Every family's financial picture is different, and the right structure depends on the parents' total assets, their health, and timeline.

Is Legal Planning Always Necessary Before Building an ADU?

Not every family needs a complicated trust or deed. A single homeowner building an ADU for rental income, or a family with one child and a fairly simple estate, might only need some basic documents like a power of attorney, a healthcare proxy, and a basic will. The cost for foundational estate planning in Massachusetts ranges from roughly $1,500 for a single person to $3,100 for a married couple. But more complicated situations can be up to $10,000 for the trust planning.

We recommend that every ADU family consult with an estate planning attorney before construction. But of course not every family's situation is the same. If you're building an ADU as a rental unit and not for family to live in, the ownership question is pretty simple. You own the property, so you own the ADU. The legal planning for that scenario is minimal. Our concern is specifically for families where the ADU occupant has a financial or emotional stake in the building and no legal protection.

What Should Every Family Do Before Breaking Ground on an ADU?

We tell every client the same thing. Building an ADU requires a team of three people working together from day one. You need a mortgage professional, a qualified estate planning attorney, and a builder. All three need to be in communication early, because the financing, the legal structure, and the building plan all have to work together.

Start with the ownership question. Who will live in the ADU? Are they contributing financially? Do they expect any ownership interest? Are there other family members who could have issues with the arrangement? Are there health concerns that could lead to MassHealth eligibility questions in the next five years?

If you can answer those questions honestly as a family, you are ready to engage professionals. If you can't, that's pretty normal. Attorney Nunes says that families need to communicate and be honest with themselves, which is not always easy. The families who do the hard work to all get on the same page before construction starts will be able to build successfully. Massachusetts homeowners can review the state's by-right ADU requirements at mass.gov.

Your ADU Belongs to You. Make Sure the People Inside It Are Protected.

The ownership reality of an ADU really isn't complicated. The structure belongs to the property owner. The people living in it are legally vulnerable unless you get legal documents in place. That planning costs only a very small amount of the ADU budget, and it protects relationships that are worth so much more than the building. Do not wait until there's already problems to start the conversation.