Colo. Rev. Stat. § 22-30-121.5
When there is a reorganization under the provisions of this article and the final approved plan of organization requires an election concerning financial matters, the chair of the committee shall call for a special election concerning financial matters in the new or annexing school district. The special election shall be held on the date specified in the final approved plan of organization and may be held in conjunction with the election on the approved plan of organization. If a mill levy increase is required under the final approved plan of organization for any territory affected by the final approved plan of organization, approval of such a mill levy increase by the eligible electors residing in such territory is a prerequisite to adoption of the final approved plan of organization.
C.R.S. § 22-30-121.5