RCW 19.77 sets out Washington's trademark registration law. Washington's law is modeled after the Model State Trademark Bill (MSTB).For information about Corporate Names and State Trademarks Contact: Office of the Secretary of State Corporations and Charities Division Registering a Washington trade name (DBA) allows your business to use a name that isn't its legal business name. This guide shows you how to get one. We've got all the information you need on how to conduct an Washington business search, plus LLC naming rules, trade names and registering your business. Your business's name must end with the words "Limited Liability Company" or "Limited Liability Co.," or the abbreviation "LLC" or "LLC". Once you've found a suitable trademark name, prepare then submit an application to the USPTO. Start using your name as a trademark, and put the â„¢ symbol after it in every prominent place you use it. In Washington D.C., a trade name is filed with the Superintendent of Corporations of DCRA.