A Washington Extension Request is an application that can be submitted to the Washington State Department of Revenue to request an extension to file a tax return. This application can be used for all types of Washington State taxes including state income tax, business & occupation tax, sales & use tax, public utility tax, and more. There are three types of Washington Extension Requests: Automatic Extension, Extension by Mail, and Extension by Electronic Filing. An Automatic Extension allows a taxpayer to file their return up to 6 months after the due date without having to submit an extension request. An Extension by Mail is an application that can be filled out and mailed to the Department of Revenue to request an extension of up to 6 months. An Extension by Electronic Filing is an online application that can be submitted to the Department of Revenue to request an extension of up to 6 months.