This document contains temporary regulations that modify the rules relating to qualified amended returns by providing additional circumstances that end the period within which a taxpayer may file an amended return that constitutes a qualified amended return. These regulations provide that the period for filing a qualified amended return is terminated once the IRS has served a John Doe summons on a third party with respect to the taxpayer's tax liability. In addition, for taxpayers who have claimed tax benefits from undisclosed listed transactions, the regulations provide that the period for filing a qualified amended return is terminated once the IRS contacts a promoter, organizer, seller, or material advisor concerning the listed transaction. The regulations also provide that the date on which published guidance is issued announcing a settlement initiative for a listed transaction in which penalties are compromised or waived is an additional date by which a taxpayer must file a qualified amended return. The text of these temporary regulations also serves as the text of the proposed regulations set forth in the notice of proposed rulemaking on this subject published elsewhere in this issue of the Federal Register.