To verify if a name is already being used in California, check the Secretary of State website. Corporations, Limited Liability Companies, sole proprietors, general partnerships and trade names register organizational paperwork with the Secretary of State (303-894-2200). Trade name registration with the Secretary of State does NOT establish exclusive rights. However, it is required when doing business under any name other than the first and last names of the owner(s)/organizer(s). For more information, refer to the Legal Structure chapter of the Startable Business Resource Book.