Create a professional Lease Addendum with our free online template. This legally binding supplement modifies or adds new terms to an existing rental agreement without replacing the original lease. Common uses include changing rent amounts, adding or removing tenants, updating maintenance responsibilities, or incorporating new rules. Both landlord and tenant must agree to the addendum for it to be enforceable. Fill out the interactive form with guided fields, preview in real time, and download as PDF or Word. Includes electronic signature for both landlord and tenant. Valid in all 50 US states.