Colo. Rev. Stat. § 1-8.3-111
To be valid, a ballot shall be received by the appropriate local election official not later than the close of the polls, or the voter shall submit the ballot for mailing, electronic transmission, or other authorized means of delivery not later than 7:00 p.m. mountain time on the date of the election.
C.R.S. § 1-8.3-111
OFFICIAL COMMENT
Requiring that the ballot be completed by 12:01 a.m. local time on Election Day ensures that covered voters will not be able to cast a vote with knowledge of the election night returns of the jurisdiction whose ballot the voter is voting. One way in which a military-overseas ballot may be submitted for mailing by a uniformed service member is by giving the ballot to the mail clerk or designated service member responsible for handling mail for a particular unit of the uniformed services. Also allowing a valid ballot to be received by local officials through the close of the polls will increase the voting time available in those circumstances in which facsimile or other electronic transmission of voted ballots is permitted.