In real estate law, sublease (or, less formally, sandwich lease or sublet) is the name given to an arrangement in which the lessee in a lease assigns the lease to a third party, thereby making the old lessee the sublessor, and the new lessee the sublessee, or subtenant. This means you are renting and renting out the same property at the same time. For example, the owner of an office building may lease the whole building to a management company. This company may then sublease parts of the building to other people. The management company is said to sublet the property to the individual tenants by means of a sublease. In this event, the management company (which was previously the lessee under the original lease) becomes the sublessor, and the individual tenants are subtenants or sublessees. Some lease agreements contain language that forbids the practice of subleasing.

Sublessor remains liable to the original lessor for any damage to the property and for payment of rent. Often the original lessor requires a lower rent payment from the sublessor than what he or she may have originally paid, leaving a partial amount of the rent left up to the original lessor.