To do business under a name other than your legal business name, you must file a "doing business as" form, or DBA, in the jurisdiction where your business is located. The DBA only applies in the jurisdiction where you file it, but there are federal filings that give you greater privileges under your assumed business name.
What a DBA Does
Sometimes the name you choose for your business doesn't seem appropriate in a given situation. For example, "Skipping Leprechaun, LLC" might seem like a fitting name to express your business's personality -- until you decide to start selling office supplies to other businesses. At that point, a different name might better convey the professionalism that customers of an office supply business expect. Filing a DBA lets you represent yourself as, say, CorpSupply without having to start a new LLC. It protects consumers by alerting them that you're doing business using multiple names. During the DBA filing process, the filing agency checks your assumed name against others in its database to ensure it's unique, meaning your DBA is unique in the jurisdiction where you file it.
Who Uses It
As a limited liability company or corporation owner, you only need to file a DBA to use a business name other than the one you registered in your articles of organization or incorporation. If you're a sole proprietor or partnership, you might file a DBA to use a conventional business name, since your business is not a legally separate entity from you and thus is named after you. For example, without a DBA to use another name, you must call your partnership Stephanopoulos, Romano and Giuliani, if those are the partners' surnames.
How to File
The DBA is not a federal filing. It grants you the privilege of using an assumed business name within the jurisdiction where you file it, which is usually the county in which your business is located. In some places, the law requires you to announce your DBA in the local newspaper instead, while the newspaper is responsible for filing it with the authorities. Contact your city hall and secretary of state to find out whether you must file at those levels, also. DBA filing fees range between $10 and $100.
Since a DBA only protects your assumed business name at the state level at the highest, register the name as a trademark to protect it at the national level. Unlike a DBA, a trademark serves as more than a notice to consumers. It makes it illegal for other businesses to use your business name and — if you trademark them — your business logo and slogan. Use the U.S. Patent and Trademark Office's online Trademark Electronic Search System to check the availability of your DBA. Do this before attempting to register the trademark, since the registration fee of about $300 is nonrefundable, regardless of whether your name is available.