Colorado homeowners pay a median of $2,602 a year in property tax, an effective rate of 0.48%, the 47th highest of the 51 states we cover. The deadline to appeal: June 8 (county assessor). Here is who sets your value, how to challenge it and what evidence works.
Closed for 2026The 2026 protest window closed June 8, 2026 (county board appeals closed July 15, or September 15 in counties on the alternate schedule). The next window opens when 2027 reappraisal notices go out by May 1, 2027, and runs through June 8, 2027. In counties on the alternate schedule, county board decisions can come out as late as November 1, 2026; you then have 30 days from the mailing date to appeal to the Board of Assessment Appeals, district court or arbitration. Owners who did not protest in 2026 may still be able to file an abatement petition.
Step 1 - protest to the county assessor from May 1 through June 8 (postmarked, delivered or in person; next business day if June 8 falls on a weekend or holiday). Step 2 - if the assessor denies you, appeal to the County Board of Equalization by July 15 (the assessor must mail its Notice of Determination by the last working day of June). Large counties use an 'alternate' schedule: counties with more than 300,000 people must use it in reappraisal years, and any county may choose it. Under it the assessor decides by August 15, your board appeal is due September 15, and the board decides by November 1. Examples: El Paso County announced that 2026 real property protests had to reach the assessor by June 8, 2026. In Jefferson County for 2025, protests ran May 1-June 8, determinations were mailed by August 15, and board appeals were due September 15.
The assessor mails a Notice of Valuation (NOV) by May 1. It shows last year's and this year's actual value and comes with a protest form. In an intervening year (like 2026), a county may mail a separate notice only to owners whose value changed, and count the tax bill as the notice for everyone else. You can protest even if your value did not change.
Where you file depends on your county. Pick yours for the office contacts, local tax figures and a step-by-step guide.
Enter the market value on your assessment notice and what you think the home would really sell for. We estimate the yearly saving if the board agrees with you.
Some states cap how fast the taxable value of a home can rise (California, Florida, Michigan and Texas homesteads, for example). If your taxable value is already held below market value by a cap, a lower market value may not lower this year's bill.
Your county assessor values your home. In Denver and Broomfield, which are combined city-and-counties, it is the city and county assessor. If the assessor turns down your protest, you appeal to the County Board of Equalization, which in most counties is the board of county commissioners (often using hearing officers it appoints). Denver and Broomfield have their own city-and-county board. Homes are valued at actual (market) value using only the market (sales) approach. Values are based on sales from a set study period and are adjusted to a fixed appraisal date. For tax years 2025 and 2026 that date is June 30, 2024. Your home's physical condition is taken as of January 1. The taxable value is a percentage of actual value set by the state. For 2026 the residential rate is 6.80% for local governments (after a 10% reduction on up to the first $700,000 of value) and 7.05% for school districts. You cannot protest the assessment rate itself. Colorado revalues all real property every two years, in odd-numbered years (2025, 2027). The even year (2026) is an 'intervening year': values normally stay the same unless something changed, such as new construction or demolition. The 2027 reappraisal will use sales up to June 30, 2026.
The protest to the assessor is the first step, and it is fairly informal. You can file it online in many counties, by mail, by email in some counties, or in person. Before you file, check your property details and the sales your county used. Many assessors post comparable-sales search tools. The assessor must give you the data used to value your home within three working days of a written request (a fee may apply).
What works in Colorado: Sales of similar homes nearby during the study period (for 2025-2026 values: sales from July 1, 2022 to June 30, 2024), adjusted for differences; Your own purchase price if you bought in an arm's-length sale during the study period; An appraisal valuing the home as of June 30, 2024 (for tax year 2026); Corrections to your property record: square footage, finished basement, bathrooms, year built, quality; Photos and repair bids showing condition problems as of January 1; Assessor's values for similar homes nearby; the law treats these as credible evidence.
Send the assessor your protest by June 8. Use the form that came with your notice, the county's online appeal, or any letter saying why the value is too high. Give your own estimate of value as of the appraisal date (June 30, 2024 for 2026) and attach support. The assessor mails a Notice of Determination. If you still disagree, appeal to the CBOE by July 15 (September 15 in alternate-schedule counties). The petition usually comes with the Notice of Determination. Your petition must state a specific dollar value. You get a hearing, often before a hearing officer, where you and the assessor present evidence. The board decides by August 5 (November 1 in alternate-schedule counties) and mails the decision within five business days. Cost: No fee to protest to the assessor or appeal to the county board.
The assessor's value has no built-in presumption of being correct. The law says there is no presumption in favor of any pending valuation, and the assessor must back up the value at county board hearings. Still, as the one appealing, you must show the assessment is wrong (Board of Assessment Appeals v. Sampson, Colo. 2005). In practice, you need evidence of a lower market value as of the appraisal date.
30 days after the county board's decision is mailed. Choose one of three options. (1) The state Board of Assessment Appeals: file a petition online and upload the county board's decision. Do not file your evidence with the petition; exhibits are due four weeks before the hearing. Hearings are usually at least four months after the petition is accepted. Fee: none for your first two petitions in a fiscal year (July 1-June 30) if you represent yourself, then $33.75 each; $101.25 if an agent or attorney files. You can appeal a BAA decision to the Colorado Court of Appeals. (2) District court in your county, for a new trial. (3) Binding arbitration: tell the county board within 30 days and pick a certified or licensed appraiser from the county's list. For a home, the arbitrator's fees and expenses are capped at $150 per case. The decision is final, with no further appeal. At any of these three, the value can be raised as well as lowered, by up to 5% above the county board's value.
The lower value is used for that year's taxes. Colorado taxes are billed the following January, so a 2026 value change shows on the bill mailed in January 2027. In the intervening year, the reappraisal-year value normally carries over unless the property changed. If you already paid and win at the BAA or in court, the county refunds the difference with interest. The next reappraisal in 2027 sets a new value, so you may need to protest again.
Market value is the standard, but by law the assessor's values for similar property similarly situated are credible evidence in an appeal. You can show that comparable neighboring homes are valued lower, but it works best alongside sales evidence. This works only in limited cases. Run the numbers with our unequal assessment calculator.
Most wins start with a mistake in the assessor's record of your home. Check it line by line.
Record card checklistAn exemption is separate from an appeal: you apply once and it cuts your taxable value every year. Check you have every one you qualify for.
For owners 65 or older on January 1 who have owned and lived in the home as their primary residence for at least 10 straight years (surviving spouses may qualify). It exempts 50% of the first $200,000 of actual value. Apply to the county assessor January 1 to July 15. Late filings accepted until August 15, but without appeal rights.
A reduced-tax classification for seniors who got the senior exemption at a previous home in 2020 or later but no longer qualify for it at their current home. Apply January 1 to March 15 (late until July 15, without appeal rights).
For honorably discharged veterans with a 100% permanent service-connected disability rating or individual unemployability, surviving spouses of veterans who already had the exemption, and Gold Star spouses. It exempts 50% of the first $200,000 of the home's actual value. Apply January 1 to July 1 (late until August 1, without appeal rights).
You can protest and appeal yourself. An agent can file for you with your written authorization; the standard protest form has an agent section. At the BAA, agents and attorneys pay a $101.25 fee per petition. Self-represented owners file their first two petitions each year free. Paid representatives who give value opinions may also be subject to Colorado's appraiser licensing rules.
Fill in your details and download a written appeal statement as a PDF or Word file. Most boards also require their own appeal form: file the form and attach this letter and your evidence to it.
Tax Appeal Map is a free information site, not a law firm or appraiser. The letter is a template, not legal advice.
Step 1 - protest to the county assessor from May 1 through June 8 (postmarked, delivered or in person; next business day if June 8 falls on a weekend or holiday). Step 2 - if the assessor denies you, appeal to the County Board of Equalization by July 15 (the assessor must mail its Notice of Determination by the last working day of June). Large counties use an 'alternate' schedule: counties with more than 300,000 people must use it in reappraisal years, and any county may choose it. Under it the assessor decides by August 15, your board appeal is due September 15, and the board decides by November 1. Examples: El Paso County announced that 2026 real property protests had to reach the assessor by June 8, 2026. In Jefferson County for 2025, protests ran May 1-June 8, determinations were mailed by August 15, and board appeals were due September 15.
With the Protest to the county assessor, then appeal to the County Board of Equalization (CBOE). Send the assessor your protest by June 8. Use the form that came with your notice, the county's online appeal, or any letter saying why the value is too high. Give your own estimate of value as of the appraisal date (June 30, 2024 for 2026) and attach support. The assessor mails a Notice of Determination. If you still disagree, appeal to the CBOE by July 15 (September 15 in alternate-schedule counties). The petition usually comes with the Notice of Determination. Your petition must state a specific dollar value. You get a hearing, often before a hearing officer, where you and the assessor present evidence. The board decides by August 5 (November 1 in alternate-schedule counties) and mails the decision within five business days.
No fee to protest to the assessor or appeal to the county board.
The protest to the assessor is the first step, and it is fairly informal. You can file it online in many counties, by mail, by email in some counties, or in person. Before you file, check your property details and the sales your county used. Many assessors post comparable-sales search tools. The assessor must give you the data used to value your home within three working days of a written request (a fee may apply).
You can appeal to the Board of Assessment Appeals (BAA), district court, or binding arbitration. 30 days after the county board's decision is mailed. Choose one of three options. (1) The state Board of Assessment Appeals: file a petition online and upload the county board's decision. Do not file your evidence with the petition; exhibits are due four weeks before the hearing. Hearings are usually at least four months after the petition is accepted. Fee: none for your first two petitions in a fiscal year (July 1-June 30) if you represent yourself, then $33.75 each; $101.25 if an agent or attorney files. You can appeal a BAA decision to the Colorado Court of Appeals. (2) District court in your county, for a new trial. (3) Binding arbitration: tell the county board within 30 days and pick a certified or licensed appraiser from the county's list. For a home, the arbitrator's fees and expenses are capped at $150 per case. The decision is final, with no further appeal. At any of these three, the value can be raised as well as lowered, by up to 5% above the county board's value.
The lower value is used for that year's taxes. Colorado taxes are billed the following January, so a 2026 value change shows on the bill mailed in January 2027. In the intervening year, the reappraisal-year value normally carries over unless the property changed. If you already paid and win at the BAA or in court, the county refunds the difference with interest. The next reappraisal in 2027 sets a new value, so you may need to protest again.
Checked 2026-10 against official Colorado sources. Local deadlines and fees can differ; confirm with your assessor or board.