This document removes regulations relating to the addition to tax in the case of a substantial understatement of income tax liability and corrects an obsolete cross reference. The Internal Revenue Code (Code) provision imposing the addition to tax and cited in the cross reference was repealed in 1989. The changes made by this document will not affect taxpayers because the addition to tax does not apply to returns with a due date after December 31, 1989 (determined without regard to extensions).