A California sublease agreement is a written arrangement that involves a residential tenant leasing their rental property to a subtenant. A California sublease agreement is a document between a current tenant (sublessor) and a subtenant for residential use.Here is a sample sublease agreement you can fill out or use as a template. Create your California sublease agreement here. Rent your unit to a subtenant and download our free template. In most cases, you'll need your landlord's permission to sublet.