If you are a company that doesn't sell tangible personal property under the retailing or wholesaling business and occupation (B&O) tax classifications, and you have customers, property or payroll in Washington, you may want to check out Washington's economic nexus worksheet/calculator.
The Washington Department of Revenue published this tool on their website recently. The worksheet/calculator is pretty elaborate.
Take and look and let me know what you think.
If you have any questions, or need assistance in determining if your company has economic nexus, please contact me at firstname.lastname@example.org.