(1) If any part of any underpayment of tax required to be shown on a return required by this chapter or if any underpayment is finally assessed due to failure to file a return required by this chapter is due to fraud, there shall be added to the tax an amount equal to seventy-five percent (75%) of the portion of the underpayment which is attributable to fraud.
(2) If the State Tax Commission establishes that any portion of an underpayment is attributable to fraud, the entire underpayment shall be treated as attributable to fraud, except with respect to any portion of the underpayment which the taxpayer establishes by a preponderance of the evidence is not attributable to fraud.
(3) In the case of a joint return, this section shall not apply with respect to a spouse unless some part of the underpayment is due to the fraud of the spouse.