When you register your business with your state, you pick a name and put it on the formation documents you file with the state to ask the state to let you use that name as the official legal business name.

Maybe you’ll also file an assumed name application if you’d like to use a different name with the public than the legal business name.

On paper, then, you have a legal business name and perhaps an assumed name for the business. That DOESN’T mean you have the right to use either of those names publicly in connection with your business. That may seem all kinds of wrong, but it’s accurate.

Trademark rights are indeed a completely separate issue—at the federal level (via the U.S. Patent and Trademark Office), the state level, or even at common law (which is use without registration and based on actual use in commerce). Trademark rights are about who owns the right to use that business name with the public.

If you don’t have the trademark rights to a name, using it with the public is risking an accusation of trademark infringement. You need to assess your trademark rights separately before you use a name with the public.