26 CFR §1.6662-7

1. (a)Scope. The Omnibus Budget Reconciliation Act of 1993 made certain changes to the accuracy-related penalty in section 6662. This section provides rules reflecting those changes.
2. (b)No disclosure exception for negligence penalty. The penalty for negligence in section 6662(b)(1) may not be avoided by disclosure of a return position.
3. (c)Disclosure standard for other penalties is reasonable basis. The penalties for disregarding rules or regulations in section 6662(b)(1) and for a substantial understatement of income tax in section 6662(b)(2) may be avoided by adequate disclosure of a return position only if the position has at least a reasonable basis. See § 1.6662-3(c) and §§ 1.6662-4(e) and (f) for other applicable disclosure rules.
4. (d)Reasonable basis. For purposes of §§ 1.6662-3(c) and 1.6662-4(e) and (f) (relating to methods of making adequate disclosure), the provisions of § 1.6662-3(b)(3) apply in determining whether a return position has a reasonable basis.