A Washington sublease agreement is a contract used when a tenant wants to rent part or all of their residence to another person. Like the master lease, it requires proper documentation.This is achieved through the establishment of a sublease agreement. Notices: A sublessor must give a subtenant 14 days' written notice to pay rent or leave the property. However, Washington law doesn't lay out a formal process for sublease approval. Here is a sample sublease agreement you can fill out or use as a template. ☐ - No Move-In Inspection. When you're letting your tenant sublease the place, it's a good idea to encourage them to make sure all the paperwork is done right and legally. The Washington sublease agreement is most often performed when an individual must vacate a property they are contractually obligated to rent. Residential Rental Forms.