Embrace subletting in California! Know your rights, follow guidelines, and have a solid sublease agreement.The California sublease agreement is a legal document that binds the current tenant of a rental property (the "sublessor") to a new tenant (the "sublessee") A sublease agreement is a legal document allowing existing tenants to rent out their rented space to another party, the subtenant. California Tenants – A Guide to Residential Tenants' and Landlords' Rights and. A sublet, or sublease agreement, adds someone new to an existing lease. Usually the new person (subletter) replaces someone who is moving out. If you find yourself unable to fulfill a lease agreement for a Riverside rental, you might have the option to sublet. If you would like to sublease your apartment, you must first tell your landlord that you want to do this. A rental agreement in California is a legally binding contract that establishes the terms and conditions between a landlord and a tenant.