What is the rule for DBA?
The rule for DBA is pretty simple. If you are doing business in a state,county, or city under a name that is different than your company's legal name (the name that appears on its Articles of Incorporation or Articles of Organization) or different from your own name, if you are a sole proprietor - you must register the new name as a DBA (also known as an assumed name or a fictitious name).
For example, if ABC Corp. owns ABC Pharmacy, it should register "ABC Pharmacy" as a DBA name. It can then continue doing business just as ABC Pharmacy. It would use the full name, ABC Corp. d/b/a ABC Pharmacy on official applications that require companies to disclose all of the names they use.