As far as I'm aware, in order to be convicted of a criminal act, the prosecution must prove criminal intent.
If someone racks up hundreds of thousands of dollars on credit cards, then declares bankruptcy, that sounds like criminal intent (may not be the easiest to prove, but at the very least it is circumstantial)
If someone inflates his income by thousands of dollars, and pays his credit card regularly, there isn't any criminal intent, and he wont be convicted.