For the privilege of engaging in business activities, Washington imposes a tax measured by the application of rates against value of products, gross proceeds of sales, or gross income of the business, as the case may be. Business is defined as including "all activities engaged in with the object of gain, benefit, or advantage to the taxpayer or to another person or class, directly or indirectly." This is an extremely broad base for taxation and, consequently, this tax has been one of great interest to the legislature, especially in recent years when it has provided considerable revenue for the state. As will be pointed out subsequently, the legislature has done much in keeping this tax as controversy free as possible by modifying, clarifying, and eliminating objections raised by the courts and also by incorporating desirable decisions of the courts into the statutes. Most objections to the statutes have been litigated. Therefore this tax has the advantage of being well defined and settled as far as its basic principles are concerned. However, it is still a frequent source of litigation because of new or different types of businesses that are developed or enter the state or because of extensions of the tax by the legislature.
William L. Carter,
The Scope of Washington's Business and Occupation Tax,
35 Wash. L. Rev. & St. B.J.
Available at: https://digitalcommons.law.uw.edu/wlr/vol35/iss1/6