FAQ - Do I need to register my out of state business in Washington State?
My business was formed in another state, do I need to register in Washington State if I am doing business there?
The Washington Secretary of State's office, Corporations and Charities Division does not evaluate or determine if a business qualifies as "doing business" in Washington State. Businesses are encouraged to seek legal advice to answer this question because it involves several topics like business liability, personal liability, business licensing, taxation and others. The Corporations and Charities Division will help you with the appropriate filing once you have made your decision.
Laws that may apply to out of state registration with the Secretary of State's Office can be found here as reference RCW 23.95 Article 5 Foreign Entities.