Section 6662 imposes an accuracy-related penalty on any portion of an underpayment of tax required to be shown on a return that is attributable to one or more of the following:
Negligence or disregard of rules or regulations;
Any substantial understatement of income tax;
Any substantial valuation misstatement under chapter 1;
Any substantial overstatement of pension liabilities; or
Any substantial estate or gift tax valuation understatement.