Washington Revised Code Title 59. Landlord and Tenant § 59.20.160. Moneys paid as deposit or security for performance by tenant--Written rental agreement to specify terms and conditions for retention by landlord

If any moneys are paid to the landlord by the tenant as a deposit or as security for performance of the tenant's obligations in a written rental agreement, such rental agreement shall include the terms and conditions under which the deposit or portion thereof may be withheld by the landlord upon termination of the rental agreement. If all or part of the deposit may be withheld to indemnify the landlord for damages to the mobile home space for which the tenant is responsible, the rental agreement shall so specify. It is unlawful to charge or collect a deposit or security for performance if the parties have not entered into a written rental agreement.