A person who is leasing a residential property such as an apartment or home (tenant) may want to have a roommate stay at the leased premises. This is often a boyfriend or girlfriend but may also be a friend or family member who needs a place to stay for a short period of time—which then becomes a longer period of time.

If the tenant’s relationship with their guest takes a turn for the worse, or if the guest overstays their welcome, the tenant may not be able to remove or evict the guest from the leased premises (apartment or house) as quickly as the tenant imagined. Laws vary from state to state, but in some states such a guest who is not on the lease may become a legal tenant with certain rights after staying at the leased premises for a certain period of time. For example, the guest may become a month-to-month tenant with the right to at least 30 days written notice to move out or vacate the leased premises.

Having a roommate who has not been approved by the landlord and who has not signed and agreed to the terms of the lease agreement (is not on the lease) can cause additional legal problems for the tenant who signed the lease agreement. For example, most residential lease agreements limit the number of days (and nights) a person who has not signed the lease agreement (a guest) can stay at the leased premises. If a tenant violates this provision of the lease agreement by having guests for longer periods of time, the landlord may be able to terminate the lease and evict the tenant.

In Connecticut, tenants who wish to have a roommate stay in their leased residential property should be aware of the legal implications. If a guest, such as a boyfriend, girlfriend, friend, or family member, stays for an extended period, they may establish tenancy rights, even without being on the lease. Connecticut law recognizes that a person who occupies a property with the landlord's consent and contributes to rent or household expenses can be considered a tenant, thereby requiring formal eviction procedures to remove them if they overstay their welcome. This typically involves providing at least a 30-day written notice for month-to-month tenants. Additionally, most lease agreements have clauses that restrict the duration a guest can stay, and violating these terms can lead to the landlord terminating the lease and evicting the tenant. Therefore, it is crucial for tenants to review their lease agreement and obtain the landlord's approval before allowing someone to move in or stay for an extended period to avoid potential legal issues.