This page includes forms, fees, and instructions for all domestic business entities, foreign and domestic Registered Agents, and Washington Trademarks. For standard corporations, tax filing is with Form 1120.A corporate name MUST contain the word "corporation," "incorporated," "company," or "limited," or the abbreviation "corp. Find out how to incorporate your business in Washington, including what forms are needed, how to file the paperwork, how long it takes, and more. Eight easy steps to successfully launching your new corporation today.