Quick answerColorado sells tax lien certificates for unpaid property taxes. Lien buyers can earn Federal discount rate (Federal Reserve Bank of Kansas City) in effect Sept. 1 plus 9 percentage points, rounded to the nearest whole percent, set Oct. 1 and fixed for the life of the certificate (C.R.S. §39-12-103) — e.g. 14% for certificates in the Oct. 1, 2025-Sept. 30, 2026 period, 13% announced by El Paso County for its 2026 sale (a county announcement; the statewide rate is whatever the formula sets each Oct. 1). Interest accrues only on taxes/subsequent taxes, not on any premium bid. Redemption: Owner may redeem at any time before issuance of a treasurer's deed / completion of the treasurer's deed public auction; the lienholder may apply for that auction no sooner than 3 years from the date of the tax lien sale (C.R.S. §§39-12-103, 39-11.5-102) Sales: Annual county treasurer tax lien sales in the fall, typically October-November (most counties in November) Governing law: Colorado Revised Statutes Title 39, Articles 11 and 12 (§§39-11-101 et seq., 39-12-103) and Article 11.5 (§§39-11.5-101 et seq.) for treasurer's deed auctions.