Washington State imposes a Business and Occupation (B&O) tax which is a gross receipts excise tax. It is measured on the value of products, gross proceeds of sale, or gross income of a company conducting business in Washington. It applies to the gross income of the business. No deduction is allowed for labor, materials, taxes or other costs of doing business.
The appropriate B&O tax classification depends on the nature of the business activity. Different tax classifications with different rates apply for various business activities. Businesses performing more than one activity may be subject to tax under one or more B&O tax classifications.
Beginning Jan. 1, 2020, the nexus threshold for all B&O tax classifications and sales tax collection will be $100,000 of combined gross receipts per calendar year for businesses without a physical presence nexus. Physical presence nexus will also establish nexus for all B&O tax classifications and sales tax collection.
Physical presence nexus creating activities include, but are not limited to:
Register at https://dor.wa.gov/doing-business/register-my-business
Once you are registered, you will receive information about filing. Monthly returns are due on the 25th of the following month; quarterly returns are due by the end of the month following the close of the quarter; and the due date for the annual returns changed from January 31 to April 15.