A DBA is by no means required in order to form an LLC. For the most part, a DBA is only necessary if you're: 1) an unregistered business hoping to operate under a name other than your own legal name, or 2) a registered business entity looking to rebrand to reach a new market or describe a new product/service. Most LLCs simply conduct business under the name they register at the time of formation.
Big John's Ragin' Cajun Food Truck is one example of a company doing business under its legal name versus a DBA.
The two most common filers of DBAs are:
Adopting a DBA is especially useful for sole proprietorships. Without a DBA, a sole proprietor must operate under their personal legal name. However, with a DBA, "John Doe" could operate and accept payment under the name "Best Cut Carpentry." Without registering a trade name, John would only be able to accept checks made out to "John Doe."
Note: In order to accept payments under a trade name, you must first set up a business bank account using your confirmed DBA.
LLCS AND PARTNERSHIPS
Although DBAs are most popular among sole proprietorships, they're also great for established LLCs and partnerships looking to get into a new line of business. For example, if "Babe's Hardware, LLC" wanted to expand into furniture sales and restoration, the owner(s) might file for the trade name, "Babe's Furniture." This would allow them to promote the business as a furniture store and accept payments under the name "Babe's Furniture."
Keep in mind, however, that you'll still need to use the entity's official name on all government documents.
The DBA filing process varies significantly from state to state. In most places, you can apply through the local county clerk's office for a filing fee of between $10 and $100. You may also need to publish notice of the DBA in a local newspaper.