Our free online guide for business owners covers Washington sales tax registration, collecting, filing, due dates, nexus obligations, and more. Sellers that make sales to Canadian residents and deliver the products to instate businesses must collect and remit retail sales tax from the Canadian buyer.Submit the completed form to our office. International Chamber of Commerce is the voice of world business championing the global economy as a force for economic growth, job creation and prosperity. Engaging in or completing the customer's product sales;. Forms ; FORMSINSTOSF, Stocked Standard Forms SF Available from GSA Global Supply 2019, General Purpose and Miscellaneous. Businesses That Collect Sales Tax. Second, the case is a reminder that use of Amazon's FBA program may create physical nexus in a state. Specifically, for purposes of these instructions, a withholding agent may rely on the following provisions in connection with completing Form 1042-S. Washington relies on the sales tax, the business and occupation.