Colo. Rev. Stat. § 39-10-110
During the month of September, the treasurer shall publish for one time only in a newspaper published in his county a notice listing the names and addresses of all persons whose taxes on personal property are unpaid and delinquent, with the amount of such taxes and delinquent interest thereon to and including the last day of September, plus the fee prescribed in section 30-1-102, C.R.S. Such notice shall recite that, if the amount of such delinquent taxes, delinquent interest, and fee is not paid by the last day of September, the personal property upon which such taxes were levied shall be subject to distraint, seizure, and sale. If there is no newspaper published in the county, then the treasurer shall conspicuously post copies of such notice in the county courthouse, in the treasurer's office, and in at least one other public place in the county seat.
C.R.S. § 39-10-110