A Washington lease agreement is a document that outlines the terms of a rental between a landlord and a tenant. Our template of a Washington apartment lease agreement includes key provisions and legal requirements for a successful rental experience in Washington.How do I fill this out? Filling out this lease agreement is straightforward. Prepare a printable, Washington rental application form to verify potential tenants. You should fill out the Washington apartment lease once you are ready to sign a lease contract. Verbal rental agreements are legal in Washington State and are considered to be month-to-month tenancies. Create an attorneydrafted Washington lease agreement with stepbystep guidance. Download to PDF or MS Word. The day that rent is due will be determined in your rental agreement or in a verbal contract with your landlord.