Colorado Revised Statutes Title 39. Taxation § 39-11-115. To whom tax lien shall be sold

(1) When the taxes levied for the preceding year or years on any lands remain unpaid, the tax liens on such lands offered at public auction at the times provided by law shall be sold to the persons who pay therefor the taxes, delinquent interest, and fees then due thereon or who further pay the largest amount in excess of said taxes, delinquent interest, and fees. The excess amount shall be credited to the county general fund. Each tax lien shall be sold for an entire piece of property. The taxes, delinquent interest, and fees shall draw interest at the rates fixed by law, and, when the tax liens on any lands are bid in by the county, city, town, or city and county, the amount for which they are bid in shall draw interest at the same rates. Real property for which a tax lien is sold may be redeemed in the manner provided by law.

(2) In order that the public auction may be conducted in an efficient and equitable manner, the treasurer is hereby granted broad powers to set bidding rules governing the public auction. Such powers shall include, but need not be limited to, the following:

(3) The treasurer may combine and sell as a unit parcels which are contiguous or are contained within one subdivision.

(4) The treasurer shall announce bidding rules at the beginning of the public auction, and the rules announced shall apply to all bidders throughout the public auction. If the public auction is conducted by means of the internet or other electronic medium, the treasurer shall cause the internet bidding rules to be posted on the medium for at least two weeks before the date of sale. The internet bidding rules posted shall apply to all bidders throughout the public auction.