reportable transaction understatement
(1) In general The term “reportable transaction understatement” means the sum of— (A) the product of— (i) the amount of the increase (if any) in taxable income which results from a difference between the proper tax treatment of an item to which this section applies and the taxpayer’s treatment of such item (as shown on the taxpayer’s return of tax), and (ii) the highest rate of tax imposed by section 1 ( section 11 in the case of a taxpayer which is a corporation), and (B) the amount of the decrease (if any) in the aggregate amount of credits determined under subtitle A which results from a difference between the taxpayer’s treatment of an item to which this section applies (as shown on the taxpayer’s return of tax) and the proper tax treatment of such item. For purposes of subparagraph (A), any reduction of the excess of deductions allowed for the taxable year over gross income for such year, and any reduction in the amount of capital losses which would (without regard to section 1211 ) be allowed for such year, shall be treated as an increase in taxable income.