All Washington Resale Certificates expire on December 31, 2009. You must now apply for a Reseller’s Permit. The Washington Department of Revenue has the application available at http://dor.wa.gov/docs/forms/misc/appwastateresellerpermit.pdf
If you are a retailer, you can not honor the old Resale Certificate after December 31, 2009. Your customers must have a Reseller’s Permit in order for you to disregard sales tax on their purchase.