Subsection (a) shall not apply to a power the exercise of which can only affect the beneficial enjoyment of the income for a period commencing after the occurrence of an event such that a grantor would not be treated as the owner under section 673 if the power were a reversionary interest. But the grantor may be treated as the owner after the occurrence of such event unless the power is relinquished.
26 U.S. Code § 676 - Power to revoke
1986—Subsec. (b)(2). Pub. L. 99–514 substituted “occurrence of event” for “expiration of 10-year period” in heading and in text substituted “the occurrence of an event” for “the expiration of a period” and “the occurrence of such event” for “the expiration of such period”.
Amendment by Pub. L. 99–514 applicable with respect to transfers in trust made after Mar. 1, 1986, except for transfers pursuant to a certain binding property settlement agreement, see section 1402(c) of Pub. L. 99–514, set out as a note under section 673 of this title.