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Boulder County tax sales, Colorado
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Boulder County also sells in person, at the county courthouse in downtown Boulder, with registration at 7:30 a.m. on the day of the sale and an auctioneer conducting open premium bidding in the order of the published list. The Treasurer's sale page publishes the 2026 date, the 13 percent rate for liens sold in 2026, and a five year history table: the November 14, 2025 sale drew 25 investors for 520 properties at auction and collected $5,676,649.59 in taxes, at a 5.6 percent premium average. The Treasurer retains all certificates of purchase for safekeeping and mails copies within a week. Two Boulder specifics stand out: delinquent mobile home taxes are struck off to the county instead of being sold, and the county states plainly that it does not offer tax lien certificates over the counter. No deposit amount and no buyer payment method were published on the Treasurer's pages read, so both are marked unverified here.
Selling office: Boulder County Treasurer
Next sale: Friday, November 13, 2026, Real Property Tax Lien Sale, in person in Boulder; upcoming as of November 9, 2026. The Treasurer's Tax Lien Sale page states the 2026 real property tax lien sale will be held November 13, 2026, with registration beginning at 7:30 a.m. and the sale beginning at 8:30 a.m. The Treasurer held an information briefing before the sale, and the advertised list of properties is posted on the Treasurer's website and updated each Friday. The interest rate for liens sold in 2026 is 13 percent per year. Delinquent mobile home taxes will be struck off to the county instead of being sold at auction.
The Treasurer publishes a five year history on the sale page: 520 properties at auction and $5,676,649.59 in taxes collected at the November 14, 2025 sale, with 25 investors attending. The 2026 advertised list, updated each Friday, is the live document to watch into November 13, 2026. Treasurer's office: 1325 Pearl Street, Boulder, CO 80302, phone 303-441-3520.
Dates and deadlines
| Next sale | Friday, November 13, 2026, Real Property Tax Lien Sale, in person in Boulder; upcoming as of November 9, 2026 |
| The sale | The annual real property tax lien sale is held in person at the Boulder County Courthouse, 1325 Pearl Street, Third Floor, Boulder, CO 80302. The 2026 sale is November 13, 2026: registration begins at 7:30 a.m., the sale begins at 8:30 a.m., and the auction runs until all properties are sold or until 5 p.m., although in recent years it has not gone past 3 p.m. Delinquent mobile home taxes are struck off to the county instead of being sold at auction. |
| The list | The list of properties going to auction is published in the county newspaper of record four weeks before the sale for three consecutive weeks, under CRS 39-11-102; in the last week before the sale it is also published in the Longmont Daily Times-Call (the current paper of record) and other county papers named on the Treasurer's FAQ page. Copies are available in the Treasurer's Office at 1325 Pearl Street, and a current list is posted on the Treasurer's website near the sale and updated weekly, each Friday in 2026. The list is published in alphabetical order by owner name, and owners who pay after advertisement are removed. |
| Registration | Registration opens at 7:30 a.m. on the day of the sale at the courthouse. To register, provide your name, your address for checks and correspondence, your Social Security or Tax ID number, and a completed, signed IRS W-9 form. The exact spelling of the name registered becomes the name used on the tax lien certificate. Registered bidders receive an eight hour parking pass for the downtown city parking lots named on the FAQ page. |
| Bidding and the certificate | An auctioneer conducts open bidding, with no rotation through bidders in a predetermined order; the bid amount is the premium amount, the amount over and above the taxes, interest and fees on the day of sale list, under CRS 39-11-115(1). No interest is earned on a premium bid and the premium is not returned; premium money goes directly to the County General Fund. For the last five years premium bids have averaged from 5 percent to 7.6 percent, and the 2025 premium average was 5.6 percent, per the Treasurer. The Treasurer may combine properties under the same ownership and sell them as a group. The buyer receives a certificate of purchase, a lien only, with no right, title or interest in the property; the Treasurer retains all certificates for safekeeping and mails copies within a week following the sale. |
| Redemption | All redemptions are made through the Treasurer's office, at any time before a treasurer's deed is issued, in certified funds (cash, cashier's check or money order), paying the certificate amount plus interest at the certificate rate (13 percent for liens sold in 2026) under CRS 39-12-103, plus statutory fees; at least one month of interest always applies, as interest begins accruing once liens are sold or endorsed and is calculated monthly on the first day of the month. The holder may endorse subsequent taxes onto the certificate: the Treasurer sends endorsement notices in August, the endorsement fee is $5 per certificate, paid by the owner on redemption, and endorsed taxes earn the rate of the original lien. If the owner does not pay property taxes for three years from the date of the original sale, the holder may apply for an auction for a Certificate of Option for Treasurer's Deed under CRS Article 11.5; less than one half of 1 percent of tax liens go to tax deed, per the Treasurer. |
| Unsold liens | Boulder County does not offer tax lien certificates over the counter, per the Treasurer's FAQ, in the section headed Over-the-Counter Certificates. Under the Colorado frame, liens that draw no bid are struck off to the county; the county's stated position is that there is no over the counter purchase channel for them, and delinquent mobile home taxes are likewise struck off to the county instead of being sold. |
| Format | In person only: In person at the Boulder County Courthouse, 1325 Pearl Street, Third Floor, Boulder, Colorado; no online auction platform |
| Selling office | Boulder County Treasurer |
Sources: Boulder County Treasurer, Tax Lien Sale. Boulder County Treasurer, Tax Lien Sale Answers to Common Questions. Boulder County Treasurer, Treasurer's Deeds. Confirm with the selling office before relying on any date on this page: sales move, terms change, and parcels are pulled up to sale day.
Research Boulder County parcels before you bid
A sale list gives you the parcels, the date, and the opening terms. It does not give you the owner, the value, or the rest of the picture: liens, foreclosure status, and parcel history. PropertyRadar is the data platform for that layer. It carries owner records, assessed and market values, foreclosure and tax data, and property history for parcels across Boulder County, searchable by address, owner, or county, including parcels that never reach a sale list.
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How Colorado tax lien sales work
- Unpaid taxes become a lien, and the lien is what sells. Property taxes in Colorado are a lien on the property, and delinquent interest accrues at 1 percent per month under CRS 39-10-104.5. When taxes stay unpaid, the county treasurer publishes the delinquent list once a week for three weeks (39-11-102) and sells the tax lien at the annual sale under Title 39, Article 11. What the buyer receives is a certificate of purchase: a lien position against the property, not the property, not a deed, and no right to enter or use it.
- The sale runs every fall, and the statute sets the outer date. The sale must begin no later than the second Monday in December (39-11-109), and each treasurer fixes the day. Counties in this set sell from late October into December, most of them in November. Most of the large counties sell online through a vendor the treasurer names; some still sell in person, and the county page says which.
- Bidding is a premium, and the premium is spent money. Under 39-11-115(1) the lien goes to the person who pays the taxes, delinquent interest and fees and bids the largest amount on top of that sum. The excess, the premium, is credited to the county general fund. It earns no interest, and it is not returned if the owner redeems. Competition in Colorado raises the price of the lien without raising its return by a cent.
- The rate is fixed by statute, and redemption is the normal exit. The certificate earns the redemption rate in 39-12-103: nine percentage points above the federal discount rate as of September 1, rounded to the nearest whole percent. For the 2026 sale that rate is 13 percent. The owner, or another interested party, may redeem at any time before a treasurer's deed is issued, and the holder may pay later delinquent taxes and endorse them onto the certificate at the same rate. Most certificates end in redemption.
- The deed runs through a public auction now. Colorado used to hand the treasurer's deed to the certificate holder on application after three years. That ended July 1, 2024 under HB 24-1056, and SB 26-144 reenacted the replacement process as Article 11.5 effective June 1, 2026. After August 1 of the third calendar year following the sale, the lawful holder applies, and the treasurer auctions a certificate of option for treasurer's deed: the opening bid covers what is owed to the holder plus treasurer fees and costs, any overbid belongs to the former owner, and if no qualifying bid is made and paid, the lawful holder is deemed the option purchaser and the deed issues to that purchaser. Liens nobody buys are struck off to the county and can later be bought by assignment.
How bidding works in Boulder County
Registration is in person on the day of the sale, opening at 7:30 a.m. on November 13, 2026 at the Boulder County Courthouse, 1325 Pearl Street, Third Floor, Boulder. Bring your name and address for checks and correspondence, your Social Security or Tax ID number, and a completed, signed IRS W-9 form. No advance online registration was published on the Treasurer's pages read.
- The premium is the price, and it buys nothing. Every dollar of premium goes to the county general fund the moment the lien sells. A small lien won with a large premium can pay back less than the taxes were worth even at a 13 percent headline rate, because the rate applies only to the certificate amount. Model premium as a fee you pay for the right to earn 13 percent on somebody else's tax bill, because that is what it is.
- The certificate is not the property. No possession, no rents, no right to enter, and no deed on application. Since 2024 the deed runs through a public auction where the owner's equity is bid for openly; buyers who need the property itself on a schedule should be reading the deed state pages, not this one.
Terms: what a bid actually costs
| Deposit, Boulder County | No deposit amount was published on the Treasurer's pages read for this page, and none is claimed here. |
| Payment, Boulder County | No buyer payment method or payment deadline was published on the Treasurer's sale page or FAQ page read, and none is claimed here. The certified funds rule stated on those pages (cash, cashier's check or money order) is the rule for owners redeeming a lien through the Treasurer's office, not a published buyer payment term for the sale itself. |
| What is sold | A certificate of purchase: a lien on the property for the delinquent taxes, delinquent interest and fees. Not the property, not a deed, and no right of possession. A deed exists only at the end of the Article 11.5 public auction process, years later, if the owner never redeems. |
| The bid | The taxes, delinquent interest and fees, plus a premium bid on top. Under CRS 39-11-115(1) the premium is credited to the county general fund: it earns no interest and it is not refunded when the owner redeems. The premium is a cost of winning, never part of the return. |
| The rate | Fixed by statute, not bid. Under CRS 39-12-103 the rate is nine percentage points above the federal discount rate as of September 1, rounded to the nearest whole percent, effective October 1. For the 2026 sale the rate is 13 percent, and it applies to the taxes and fees in the certificate amount and to subsequent taxes the holder endorses, never to the premium. |
| Redemption | At any time before a treasurer's deed is issued, through the county treasurer, by paying the certificate amount plus interest at the certificate rate and the statutory fees. The holder of a redeemed certificate is paid by the treasurer; the premium stays with the county. |
| The deed path | Article 11.5, as reenacted by SB 26-144 effective June 1, 2026. After August 1 of the third calendar year following the sale, the lawful holder may apply for a treasurer's deed; the treasurer auctions a certificate of option for treasurer's deed, with an opening bid of the amount owed to the holder plus treasurer fees and costs, the premium excluded. Any overbid is the former owner's surplus. If no qualifying bid is made and paid, the lawful holder is deemed the option purchaser and the deed issues to that purchaser. County pages state a treasurer's deed is unmarketable title for at least seven years. |
| Certificate life | A certificate is not perpetual, and the deed window does not open early: the application cannot be made before August 1 of the third calendar year following the sale, and county treasurers state that certificates from sales on or after January 1, 2026 expire seven years after the sale if the deed process is never begun. |
Unsold liens: county held certificates
Boulder County does not offer tax lien certificates over the counter. That single sentence on the Treasurer's FAQ page is the county's whole published position on leftovers: liens that draw no bid are struck off to the county under CRS 39-11-108, but the county does not sell certificates over the counter afterward, so there is no assignment list, window or fee to report for Boulder County. Delinquent mobile home taxes are also struck off to the county instead of being sold at auction.
Before you bid
- Model the premium before the rate. Run the redemption case with your real premium included: certificate amount, plus premium, against 13 percent on the certificate amount alone over the likely redemption window. Liens that only work at a zero premium do not work.
- Check whether the sale is already over. Colorado's season is short and most of it lands in a few November weeks. Several sales in this set had already closed before these pages were checked. The treasurer's sale page is the live word on dates, registration, and deposits.
- Subsequent taxes are part of the position. A holder can pay later delinquent taxes on the parcel and endorse them onto the certificate at the same rate. Budget for carrying the position across the three year deed window, not just for buying it.
- Set the maximum before the sale opens. The free Max-Bid Calculator below works backwards from your exit value to the highest certificate amount you can carry, with the premium and costs shown.
Every Colorado county in this set
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