Sublease agreements are legal documents detailing the terms and conditions of the lease of a property to a new tenant. A sublet, or sublease agreement, adds someone new to an existing lease.Subleasing: A sublease is when the tenant allows another party to use the property for a period of time. Sublease Agreements are legal documents detailing the terms and condition of the lease of a property to a new tenant. A sublease agreement for Florida is required if you want to rent out the whole or parts of the property you're already renting. A sublease, or sublet, occurs when a tenant assigns part or all of their lease to a new tenant. In general, most commercial leases permit subletting. This is not recommended or legal in most leases. Most rental agreements require the landlord's written consent before subletting the property. How Does Subleasing Work?