Washington Final Accounting Supplement (WAS) is an optional form provided by the Washington State Department of Revenue for businesses to report additional information about their finances. It provides detailed information about the financial activities of a business that is not reported on the standard Washington state business tax return. WAS can be used to report the gain or loss on the sale of a business, depreciation expenses, income from rental real estate, and other items. There are two types of Washington Final Accounting Supplement forms: Form R-103 for C-Corporations and Form R-104 for all other entities.