Washington Application for Out of State Supplemental Reporting (WA USSR) is a supplemental reporting mechanism that allows non-residents of Washington State to report any changes to their Washington State tax liability or other income-related information. This is typically used by those who are employed out of state but still have Washington State tax obligations, such as military personnel, students, or those who are self-employed. WA USSR can be completed either online or by mail. There are two types of WA USSR: the Form OSSR-001, which is used for filing an annual report of any changes in Washington State taxable income, and Form OSSR-002, which is used for filing quarterly reports of any changes in Washington State tax liability. Both forms can be filed online or by mail.