There are many reasons to get a DBA for an LLC. We currently have 4 DBA`s operating under one parent LLC. This is 4 different companies with their own expenses and revenue streams but all have the same ownership structure of the LLC.
As far as when to use what name. Why not put both names on the checking account. That way no matter what name a customer makes the check out to you can still deposit it.
for legal reasons, it makes sense to use a dba as well. if you own a business, say XYZ Inc. and you operate an internet business, say abcdefg.com, since you`re "doing business" under another name, you should have a dba filed in the county where your business is based. if you registered your business in another state like Delaware or Nevada and your business is located in Ohio, that gets a little crazy (see attorney), but i would GUESS, that where ever it is you do business out of, you`d register the dba in the local county where you`re based from.
does that make sense?