When you assign a lease, you move out permanently and a new tenant moves in for the remainder of the lease term. An assignment of a lease differs from a sublet. With a sublet, the original tenant gives up an apartment temporarily. With an assignment, the original tenant gives up the apartment permanently.26
The person to whom you assign your lease is referred to as the "assignee." Both you and the assignee remain responsible to the landlord for the obligations contained in the lease.27 As the original tenant, you can escape such responsibilities only if the landlord clearly releases you from them.28
To be valid, an assignment must be in writing.29 While your lease may say that you need the landlord's permission to assign, many leases also state that the landlord cannot unreasonably deny her consent. If this is the case, the landlord cannot unreasonably deny you permission to assign.30
Where a lease does not specifically prohibit a landlord from unreasonably denying consent, she can deny her consent for any reason. If a lease forbids assignment, you assign anyway, and the landlord objects to it, the landlord can terminate your lease.31 If you then move out, the landlord will have a duty to make reasonable efforts to find a new tenant. If the landlord attempts to sue you for any rent or costs she has incurred because of your breach of the lease, you can argue that you had a person willing to take over the lease who could have paid the landlord the rent. Also, even if you do not get the landlord's permission before assigning the lease, if the landlord knowingly accepts rent from the assignee, then she is probably required to accept the assignment.32
If you are moving out, you should also arrange with the landlord to get your security deposit back if you paid one. See Chapter 3: Security Deposits and Last Month's Rent.
27 . Dwyer v. Lavigne, 319 Mass. 26 (1946), cases cited therein, and Carlton Chambers Co. v. Trask, 261 Mass. 267 (1927).
30 . If a court finds that the landlord did unreasonably deny consent to the assignment, the original tenant is not liable for the rent. Adams, Harkness & Hill, Inc., v. Northeast Realty Corp., 361 Mass. 552, 557 (1972). However, where a lease does not specifically prohibit a landlord from unreasonably denying consent before assigning or subleasing, the landlord is free to deny consent for any reason. Slavin v. Rent Control Board of Brookline, 406 Mass. 458, 463 (1990).