To buy a tax lien in Colorado you bid on a certificate, not on the property. The county certificate sale is run by the County Treasurer. You are buying the delinquent debt, the statutory interest it earns, and the right to force a sale if the owner never repays.
Each step below is drawn from Colorado statute, not general advice. The exact sale dates, platform, and deposit amounts are set county by county, so confirm the specifics on your county page before you register.
New here? Most beginners start with a certificate (the lien path). The deed steps below apply once you hold a certificate long enough to force a sale, or you bid directly at a tax deed auction. Not sure which is for you? Start with tax lien vs tax deed.
Learn the timeline and lien priority
Colorado property taxes may be paid in full or in two equal installments. The first installment is due by the last day of February and the second by June 15, or the full amount may be paid in a single payment by April 30. Delinquent interest runs at 1 percent per month from March 1 on a late first installment, from June 16 on a late second installment, and from May 1 on a late single payment. The treasurer must mail a delinquency notice to each owner no later than September 1, and the notice sets a payment date at least fifteen days out before the lien is advertised and sold. Parcels still unpaid go to the tax lien auction later that same year. Understand this before you commit any money.
Find the advertised delinquent list
Before the certificate sale, the County Treasurer advertises the delinquent parcels. The auction must commence on or before the second Monday in December each year. If the lien cannot be advertised and offered by then, the treasurer holds the sale on a later day that still allows time for the required published notice. Most counties schedule the sale during the autumn, so confirm the exact date with the county treasurer. Pull that list for your target county and shortlist the parcels worth researching.
Register, deposit, and bid
Register on the county’s certificate-sale platform and fund the required deposit. Bidding runs upward from a statutory minimum bid, and the highest bid wins. Anything you pay above that minimum is a premium, so check how your state treats it before you bid: a premium can earn a different return than the base amount, or none at all. See the Colorado rate rules. There is no statutory minimum return, so what you earn is decided at the sale. Colorado does not bid the interest rate down. Every certificate sold in a given rate year earns the same statewide rate, and competition happens through premium bidding instead. The lien opens at the taxes, delinquent interest, and fees due, and the bidder who pays the largest amount in excess wins. That excess is credited to the county general fund. It earns no interest, it is not added to the redemption amount, and it is not refunded when the owner redeems, so an aggressive premium directly reduces the investor's yield. Treasurers may also set a minimum total below which they will not accept competitive bids.
Collect interest or wait out redemption
Redemption interest runs from the date of sale on the taxes, delinquent interest, and costs for which the lien sold, and on any subsequent taxes the holder pays and has endorsed on the certificate. Portions of a month count as a whole month. The rate is not fixed in the statute. C.R.S. 39-12-103(3) sets it at nine percentage points above the Kansas City Federal Reserve Bank discount rate, rounded to the nearest full percent, and the commissioner of banking establishes it each September 1 to take effect that October 1. The rate effective October 1, 2026 is 13 percent. There is no minimum-return floor in the redemption statute. The 8 percent floor investors sometimes see quoted sits in C.R.S. 39-12-111, which covers county repayment when a lien was wrongfully sold on land that owed no tax, and it does not apply to ordinary redemptions. Redemption may be made at any time before a treasurer's deed is executed, so the practical window runs past the three-year mark and into the Article 11.5 process. Once a deed application is pending, the owner must file an intent to redeem with the treasurer no later than seven calendar days before the scheduled public auction, then pay the amount on the redemption statement while it is in effect, and must redeem the entire property. The auction itself is set 30 to 60 calendar days after the treasurer mails the notice of public auction. A separate rule lets an owner who was under a legal disability when a tax deed was executed under Article 11 redeem within nine years of the deed being recorded, at 15 percent per year plus the present value of any improvements. To redeem, the owner pays the taxes, delinquent interest, and costs for which the lien was sold, plus redemption interest from the date of sale at the rate in force, plus every subsequent tax the holder paid and had endorsed on the certificate with interest at the same rate, plus the statutory fees the purchaser paid. Portions of months count as whole months. The premium the investor bid above the taxes is not part of the redemption amount and is not returned. If they redeem, that payoff is your return; if they never do, the certificate becomes your path to the property.
Apply for a tax deed
After August 1 of the third calendar year following the tax lien sale, the lawful holder of the certificate of purchase may apply to the treasurer for a treasurer's deed. The treasurer then sells the property at a public auction, and the winning bidder receives a certificate of option for a treasurer's deed. A lawful holder who did not win may repurchase that certificate by filing a notice of intent within three business days and paying the winning bid's excess over the debt, with interest, by noon on the eighth business day. Title vests at the close of the eighth business day after the auction, and the treasurer then records the deed. On and after July 1, 2024 a treasurer may not issue a deed under Article 11, which is how Colorado answered Tyler v. Hennepin County on owner equity, and the Article 11.5 that governs now is the version SB 26-144 reenacted effective June 1, 2026. The lawful holder's bid opens the auction and must be no less than the total debt the treasurer determines: the amount due on the tax lien, interest, endorsed subsequent taxes, and the treasurer's fees and costs, itemized on a statutory bid form that the treasurer makes public. A competing bidder must beat that figure, and anything paid above it is the overbid. A treasurer may not bid in an individual capacity.
Bid at the tax deed auction
The County Treasurer sells the property at public auction to the highest bidder. The treasurer may require the applying lawful holder to deposit up to one thousand dollars plus statutory fees when the application is accepted, applied against the treasurer's fees and costs, and all Article 11.5 fees and costs are chargeable as additional amounts owing under the certificate of purchase. A third-party winner may be charged up to three hundred dollars for processing. The statute sets no bidder deposit percentage, so payment terms come from the treasurer's written auction policies. Payment of a winning bid must reach the treasurer by the date and time of the auction, or by a later time that same day the treasurer sets in writing, in the form the treasurer specifies. If the high bidder does not pay, the next highest bidder who tenders the full bid on time wins, and the treasurer may bar a non-paying bidder from these auctions for up to five years. A lawful holder who wins with a bid above the amount owed to it pays only the excess, within three business days.
Or buy over the counter
You do not have to wait for an auction. If a tax lien draws no bid, the treasurer strikes it off to the county, city, town, or city and county for the taxes, delinquent interest, and fees, and issues that government a certificate of purchase. A county holding certificates of purchase may then assign, sell, or transfer them in the manner, at the times, and on the terms set by resolution of its board of county commissioners, which is the mechanism Colorado counties use to sell county-held liens over the counter between annual sales. Availability, pricing, and whether a county offers a public list at all vary by county, so check with the treasurer. Colorado has no statewide lands-available list of the Florida type. Where a county obtained a tax deed under the pre-July-2024 process, the board of county commissioners lists that real property for sale and may repair and insure it in the meantime. Unclaimed Article 11.5 overbids, not properties, are what escheat: amounts of twenty-five dollars or more go to the state treasurer as unclaimed property two years after the auction, and smaller amounts go to the county general fund after six months.
One more step: clear the title
Winning a tax deed does not hand you marketable title. Before you can resell to a normal buyer or insure the parcel, you will usually need a quiet title action, which takes months and costs money. Fold that cost into your maximum bid and read what you actually own after a tax deed before you bid. A tax deed also does not wipe out everything: select governmental and municipal liens can survive, and a federal tax lien carries a 120-day IRS redemption right, so check what survives a tax deed too.
Buying tax liens in Colorado: common questions
How do you buy a tax lien in Colorado?
Can you buy Colorado tax liens online?
More Colorado answers, including redemption and statute detail, are on the Colorado tax sale FAQ.
New to this? Start with tax lien vs tax deed and the full Colorado walkthrough, then value a parcel with the due diligence guide.
Steps verified Oct 12, 2026 against Colorado statutes.
Tax Sale Atlas publishes educational information about public tax sale processes. This is not legal, financial, or investment advice. Rules, dates, and fees change; confirm with the office that runs the sale before you bid.