Sort of.
I think in Daschles case it was rather clear cut, he owed the money. And had to know it.
However, I do know that the tax laws are so complex that it is not possible for some people to know exactly what they owe. Sometimes checking with the government results in the IRS saying they don't know either, but to go ahead and file a certain way and if it goes through, fine.
What about the penalty if I'm wrong? You'll have to pay it.
It's a shame that code is so bad that virtually everyone is a criminal.
Arf