As of Jan. 1, 2010 Washington will not accept a resale certificate in order to exempt wholesale sales. The state now requires an application and issuance of a reseller permit before wholesale sales will be exempt from tax. Washington has made it clear that it will not permit sellers to obtain reseller permits after the fact - instead, Washington requires that reseller permits are obtained before a company is permitted to make tax-exempt wholesale purchases.
To be clear - if you don't obtain a resellers permit before a wholesale transaction - Washington will collect tax twice - first when the wholesaler buys the product and second when they sell it.
HOW DO YOU OBTAIN A PERMIT?