C.R.S. § 15-2.5-310

(1) To the extent a powerholder releases or fails to exercise a general power of appointment other than a power to withdraw property from, revoke, or amend a trust: (a) The gift-in-default clause controls the disposition of the unappointed property; or (b) If there is no gift-in-default clause or to the extent the clause is ineffective: (I) Except as otherwise provided in subparagraph (II) of this paragraph (b), the unappointed property passes to: (A) The powerholder if the powerholder is a permissible appointee and living; or (B) If the powerholder is an impermissible appointee or deceased, the powerholder’s estate if the estate is a permissible appointee; or (II) To the extent the powerholder released the power, or if there is no taker under subparagraph (I) of this paragraph (b), the unappointed property passes under a reversionary interest to the donor or to the donor’s transferee or successor in interest.