Someone is moving in. Maybe a partner, maybe a friend taking the spare room, maybe you just want to split the rent further.
Physically, that takes an afternoon. On paper it is a change to your tenancy, and whether you make that change properly determines what happens to both of you if anything goes wrong later. The person who is not on the lease has no rights under it. The person who is on the lease may be in breach for having them there.
Here is how to add a roommate or partner to your Boston lease: what the landlord can ask for, what changes once it is done, and why the informal version is worse than it looks.
What is the difference between living there and being a tenant?
Living somewhere and being a tenant are different things. Living there means occupying the unit, and being a tenant means you signed the lease.
A tenant has the rights the lease and the law give a tenant, and carries the obligations, including liability for the rent. We cover what signing commits you to in applying for a Boston apartment with roommates, which notes that an unsigned occupant has no rights under the lease and may breach it, and that they still cannot simply be locked out.
What happens if someone moves in without signing the lease?
Someone who moves in without signing is not a tenant, and the person on the lease may be in breach for having them there.
For them: no rights under the lease. They cannot enforce it, they have no say in a renewal, and they are not a party to any dispute with the landlord. Massachusetts requires a court process to remove someone who lives in a unit, so they generally cannot simply be locked out, but that is far weaker footing than a tenant has.
For you: many leases either cap occupancy or require approval for additional occupants. Having someone living there who is not on the lease can put you in breach of your own tenancy, and the consequences land on the person who signed, which is you.
What is the difference between a guest, an occupant and a tenant?
A guest is staying temporarily, an occupant lives there without being on the lease, and a tenant signed the lease. Leases usually distinguish between these three, and the words are not interchangeable.
| What it means | What they get | What the lease usually says | |
|---|---|---|---|
| Guest | Staying temporarily | Nothing. They are your visitor | Often a cap on consecutive nights before they stop counting as a guest |
| Occupant | Living there, not on the lease | No rights under the lease | Frequently requires landlord approval, sometimes prohibited outright |
| Tenant | Signed the lease | Full tenancy rights and full obligations | Added by amendment or a new lease |
The guest clause is the one worth reading closely before you assume you have time. Many leases set a specific number of nights, and someone who is clearly living there is not a guest regardless of what anyone calls them.
What will a landlord ask for when you add a roommate?
Expect the incoming person to be treated like a new applicant, because to the landlord that is what they are.
- An application and screening. Credit, income, references, sometimes a background check.
- Income documentation. Whether they are assessed on their own or as part of a combined household varies by landlord.
- Signatures on an amendment or a new lease. This is the step that actually changes anything.
- Possibly an adjusted rent or deposit. Massachusetts caps a security deposit at one month's rent. Some leases permit a rent increase when occupancy changes and some do not. Ask what yours says rather than assuming either way.
If the person moving in has thin credit or no local rental history, that is worth raising early rather than discovering at the screening stage. Our guide to vetting a roommate before signing covers what to establish between yourselves first.
What changes when a roommate signs the lease?
Three things change: you typically become liable for each other's rent, the deposit becomes a shared asset, and your renters insurance may need updating.
They usually become liable for the whole rent, and so do you, for theirs. Under a standard shared lease, each tenant is typically responsible for the full amount rather than a share. Adding someone does not divide your exposure. It adds a person who shares it.
The deposit is now a shared asset. The landlord usually holds one deposit for the unit, and how the two of you divide it when one leaves is a private matter between you. We walk through how that usually works in replacing a roommate mid-lease.
Your renters insurance may need updating. A policy in one name generally does not cover an unrelated roommate or an unmarried partner unless that person is named on it. A spouse is often covered, depending on the insurer. This is cheap to fix and easy to forget.
Is there a limit on how many people can live in a Boston apartment?
Yes, occupancy limits exist in Massachusetts, and we are not going to put a number on them.
Those limits are not the same as the number of bedrooms. A unit advertised as a four-bedroom is not automatically available to any four people, and the applicable standard depends on the unit and on local rules. Boston, for example, limits how many full-time undergraduate students can share a unit. We touch on the same point in our guide to living in Allston, where we note that occupancy limits are not always the same as the bedroom count.
The practical move is to ask the landlord directly what the unit is permitted for, before anyone makes plans. Asking in advance gives the landlord a chance to say yes before anyone has moved, and gives you time to plan if the answer is no.
If the current unit is too small for the people who will live there, you can search Boston apartments by area on Spot Easy, where every agent is verified before listings go live.
What if someone has already moved in without signing?
If someone has been living there unsigned for a while, the usual path forward is to ask the landlord, have the person apply, and sign an amendment or a new lease. Many landlords would rather document the arrangement correctly than punish a late request, but check your lease first, because an unapproved occupant can still be a lease violation.
If the situation is the other way around, and you need someone who is not on the lease to leave, that is genuinely complicated. Occupant status, notice and what you can lawfully do are fact-specific, and getting it wrong creates liability for you rather than for them. Get advice specific to your situation from a tenant-rights attorney before taking any action.
FAQ
Does my partner have to be on the lease to live with me? Often, yes. Many leases require approval for anyone living there beyond the named tenants, and some prohibit additional occupants outright. Read your lease and ask the landlord before the person moves in.
Can my landlord raise the rent for adding a roommate? Some leases permit an adjustment when occupancy changes and some do not. It depends on your lease, so ask what yours provides before you commit to a number with the person moving in.
What if they are only staying a few months? That is a guest-clause question, and guest clauses often have a night limit. If they are living there rather than visiting, the length of time does not change what they are.