2013 Updated AICPA Report on Civil Tax Penalty Reform ...

An understatement for this purpose is substantial if the amount exceeds the greater of 10 percent of the tax shown on the return or $5,000, or in the case of a corporation, the amount exceeds the lesser of 10 percent of the tax shown on the return ($10,000 if greater) or $10 million. See section 6662(d)(1). ................
................