How to Fill Out an Affidavit of Loss in Washington. In Washington State, you can use an affidavit of loss document to request a replacement for a lost title, license plates, registration, decal or tabs. The form also serves to release interest in a vehicle or marine vessel that you wish to sell or give away. If you use an affidavit of loss to sell a vehicle, you also must submit a Report of Sale to your vehicle licensing office within five days of the sale.