A sublease is an agreement between a landlord and one or more tenants. Subletting is when thirdparty rents or "subleases" the property from the original tenant.Subletting is a way to add an additional person to your existing lease. The Guide explains what you should know when applying to rent, living in a rented property, and dealing with the end of a lease. A sublease is a rental agreement where an existing tenant leases a rental property to a new tenant. A Pennsylvania sublease agreement is a legal document that a tenant (or "sublessor") enters into with a third party (or "sublessee"). Some leases in Philly allow subletting, meaning another person can live in the apartment and pay rent while you travel or work elsewhere. Subletting allows tenants to lease out their rental to a new occupant. If there is no damage to the property, the security deposit should be returned to you after you move out. Sublease Agreement: A sublease allows an existing tenant to rent out all or part of the rental unit to another party.