Colo. Rev. Stat. § 15-11-805
(1) For purposes of this article, tangible personal property in the joint possession or control of the decedent and his or her surviving spouse at the time of the decedent's death is presumed to be owned by the decedent and the decedent's spouse in joint tenancy with right of survivorship if ownership is not otherwise evidenced by a certificate of title, bill of sale, or other writing. This presumption shall not apply to:
Source: L. 99: Entire section added, p. 466, § 4, effective July 1. L. 2002: Entire section amended, p. 653, § 8, effective July 1.