I own an LLC. A collector for the Department of Education is threatening to sue me and garnish my bank accounts for payment.

Isn't that one of the purposes of an LLC? The inability to attach personal assets to business assets?

Yes and no. is the debt purely personal ?

If so, if the LLC checking is done properly, then it should be protected

BUT>>>
Do you have personal funds that go directly into it ?
Do you use it as a personal checking account paying for personal items ?

Often we set up the paper work but fail to keep the money separate in day to day activities.

But if all things correct, no they can not get the money