In a Bankruptcy case out of Florida, the debtor's income tax debt met the criteria for discharge except one according to the IRS challenge. 

11 U.S. C. Sect. 523(a)(1)(C) requires that the taxpayer-debtor cannot be guilty of a willful attempt to defeat or evade the tax. 

The taxpayer had filed all of the returns but was just unable to pay.

This is an interesting case.   If the IRS is right about their position in a general sense then  if returns are filed and not paid section 523 (a)(1)(C) is violated  in every case-  no one who owes unpaid income tax debt could discharge it.

In this case the Court looked closely at the specific facts surrounding the failure to pay the tax and decided that the taxpayer didn't "willfully" attempt to defeat the tax or evade it even though he did not pay.

Facts do make a difference and that is why an experienced attorney is important in dealing with unpaid tax debt.

 [In re Pisko, 364 B.R. 107 (Bkrtcy.M.D.Fla. 2007), ]