understatement of liability
For purposes of this section, the term “understatement of liability” means any understatement of the net amount payable with respect to any tax imposed by this title or any overstatement of the net amount creditable or refundable with respect to any such tax. Except as otherwise provided in subsection (d), the determination of whether or not there is an understatement of liability shall be made without regard to any administrative or judicial action involving the taxpayer.