C.R.S. § 39-11-149: Sales en masse valid.

If two or more noncontiguous properties or portions thereof have not been separately valued and assessed or, having been separately valued and assessed, whether having a common ownership or not, have had tax liens sold en masse for a gross sum for the nonpayment of taxes and charges, then, after seven years from the date of any tax lien sale, the assessment and tax lien sale and any certificate of purchase issued must be deemed valid and legal and considered so in all actions, suits, or proceedings in which is involved the validity of any such assessment, tax lien sale, certificate of purchase, or treasurer's deed issued in accordance with article 11.5 of this title 39. Nothing in this section alters, amends, or repeals section 39-11-148.