Colo. Rev. Stat. § 39-11-130
In case the treasurer is compelled to serve or to publish a notice in a newspaper pursuant to section 39-11-128, then before any person who may have a right to redeem the land, lot, or claim from the tax sale is permitted to redeem, the person shall pay the officer or person who by law is authorized to receive such redemption money the entire amount paid by the applicant for a tax deed for such notices, for abstract and search fees, for the cost of publishing such notices for the use of the person compelled to pay such charges, and for amounts paid to third parties for computer software costs incurred in connection with processing the redemption. If the property therein described is redeemed before the expiration of the period of redemption named in such notice, the purchaser or the purchaser's assigns shall recover, in addition to the purchaser's interest and costs, the cost of such publication and the abstract and search fee.
C.R.S. § 39-11-130