Dec 2nd 2010
As I have stated previously, in June 2010, Washington adopted “economic nexus” for businesses that report under apportionable business and occupation tax classifications. For these classifications, your business does not need to have a physical presence to have nexus and be subject to Washington tax. With the adoption of economic nexus, Washington also changed the way businesses apportion their taxable income between Washington and other states and countries. For more info, check out Washington's website where they have added an online video tutorial.