26 CFR 20.6011-4: -4 Requirement of statement disclosing participation in certain transactions by taxpayers.

(a) In general. If a transaction is identified as a listed transaction or a transaction of interest as defined in § 1.6011-4 of this chapter by the Commissioner in published guidance (see § 601.601(d)(2)(ii)(b) of this chapter), and the listed transaction or transaction of interest involves an estate tax under chapter 11 of subtitle B of the Internal Revenue Code, the transaction must be disclosed in the manner stated in such published guidance.

(b) Effective/applicability date. This section applies to listed transactions entered into on or after January 1, 2003. This section applies to transactions of interest entered into on or after November 2, 2006.