(1) If the underpayment of a tax by a taxpayer is attributable to a reportable transaction, the taxpayer is subject to a penalty that is equal to the product of:
(a) 10%; and
(b) the amount of the tax underpayment attributable to the reportable transaction.
(2) If a taxpayer amends an income tax return to change the tax treatment of a reportable transaction after the day on which the commission contacts the taxpayer regarding the examination of the income tax return, that change in the tax treatment of the reportable transaction contained in the amended income tax return may not be considered in determining a tax underpayment under this section.
(3) A penalty imposed by this section is in addition to any other penalty imposed by this title.