If only one spouse files a gift tax return within the time provided for signifying consent, the consent of both spouses shall be signified on that return. However, whereover possible, the notice of the consent is to be shown on both returns and it is preferred that the notice be executed in the manner described in subdivision (i) of this subparagraph. The consent may be revoked only as provided in § 25.2513-3 . If one spouse files more than one gift tax return for a calendar period on or before the due date of the return, the last return so filed shall, for the purpose of determining whether a consent has been signified, be considered as the return. (See §§ 25.6075-1 and 25.6075-2 for the due date of a gift tax return.)
26 C.F.R. §25.2513-2