How to Protest Your Denver Property Tax Assessment

To protest a Denver property tax assessment, file a written objection with the Denver Assessor’s Office by June 8 of the assessment year, backed by comparable sales from the state-defined data period showing your home’s value is too high.¹ Colorado revalues all real property in odd-numbered years and mails Notices of Valuation by May 1, so you have roughly five weeks to review the figure and decide whether to challenge it.² Even a small reduction in actual value translates into real money each year, so the effort pays off when the assigned value looks inflated.

What the Assessor Is Actually Valuing

Denver’s assessor is not estimating what your home would sell for today. Colorado law requires residential valuations to rest on comparable sales from an 18-month period ending June 30 of the year before the assessment.³ For the 2025 cycle (which sets values for 2025 and 2026 taxes), that window runs from roughly January 2023 through June 30, 2024. The assessor can extend the window backward in six-month increments up to five years if comparable data is thin, and each sale used to support your value is adjusted to reflect market conditions as of the June 30 cutoff.

Residential property in Colorado is valued using the market approach only, meaning the assessor looks at what similar homes actually sold for rather than replacement cost or rental income.⁴ That matters for your protest: your strongest evidence will always be comparable sales from the correct period, not appraisals built on cost or income methods, and not what the house across the street listed for last month.

Grounds That Work and Grounds That Don’t

Successful protests almost always fall into one of two buckets: factual errors in the property record, or an actual value that exceeds what comparable sales support.

Start with the record. Pull up the assessor’s detailed property record through the Denver Assessor’s online database and check it against reality. The file might show a finished basement when yours is unfinished, add a bathroom that doesn’t exist, overstate square footage, or list the wrong lot size. Those data errors inflate value directly, and correcting them is usually the easiest path to a reduction.

If the record is right but the number still looks high, your argument has to be that the comparable sales behind it don’t reflect your home’s real market position. You’re looking for sales of similar homes (square footage, age, condition, lot size, neighborhood) within the data collection period that closed for less than your assessed value. Three to five strong comparables make a compelling case. When a comparable has an advantage your home lacks, say a renovated kitchen or a larger garage, you can argue the price difference supports a lower value for your property.

External conditions that depressed market value during the data period count too: a busy road built nearby, commercial development that changed neighborhood character, environmental problems in the area. The key is showing the market actually reflected those conditions through sale prices, not just arguing the nuisance exists.

Some arguments go nowhere. Personal financial hardship is irrelevant; the assessor’s job is to estimate market value, not affordability. General complaints about rising taxes or disagreement with the assessment rate itself are not valid grounds either.¹

Gathering Evidence from the Right Period

Every piece of evidence has to tie back to the correct data collection window. If the base period ended June 30, 2024, a sale from October 2024 is irrelevant no matter how favorable the price. Search the Denver Assessor’s sales database for properties matching your home’s key characteristics that sold inside the window. Start in your immediate neighborhood, then expand to comparable areas if the data is thin. For each sale, note price, date, square footage, lot size, age, condition, and any features that differ from your property.

Photographs of physical problems strengthen a comparables-based case. Foundation issues, an aging roof, outdated systems, deferred maintenance: all of these reduce what a buyer would pay. Take clear, dated photos and be ready to explain how each issue affects market value. Contractor estimates for repairs help.

A professional appraisal isn’t required, but it can carry weight when the gap is large. Residential appraisals for tax protest purposes typically run $450 to $1,500 depending on complexity. If you hire an appraiser, confirm they’re using the correct base period date and comparable sales window, not today’s market.

Filing the Protest

The protest window opens the first working day after Notices of Valuation go out (typically early May) and closes on June 8.¹ The deadline is firm. A mailed protest must be postmarked by June 8; a hand-delivered one gets stamped on arrival. Late protests are rejected regardless of merit.

You can file three ways: using the protest form that came with your Notice of Valuation, with a written letter stating your objections, or through the Denver Assessor’s electronic filing system. The form asks for your property’s schedule number (printed at the top of the Notice of Valuation), your estimate of the correct value, and the reasons for the objection. Whichever format you pick, include your comparable sales data and any supporting photos or documents. Electronic filing gives you an immediate confirmation receipt, which ends any argument about whether you met the deadline.

Paper protests go to the Denver Assessor’s Office at the Wellington Webb Municipal Building, 201 West Colfax Avenue, Denver, CO 80202. Use certified mail or a certificate of mailing. A regular stamp is legally sufficient, but you lose your ability to prove timely filing if the envelope disappears.

The assessor’s staff holds hearings from June 15 through July 5 to review protests.⁵ You may be invited to walk through your evidence. Come ready to discuss each comparable and explain why it supports a lower value. The assessor’s team usually has their own set of comparables, and the conversation is essentially a negotiation about which sales best represent your property.

After the Decision: The Notice of Determination

Once the review is done, the assessor mails a Notice of Determination that either adjusts or holds the original value. For real property, the notice must go out in time for you to meet the July 15 appeal deadline, so expect it by early to mid-July.⁶ The notice includes the assessor’s reasoning, the value applied, and information about your right to appeal.

If the value was reduced and you’re satisfied, you’re done. Your tax bill for the current cycle will reflect the lower figure, and if you escrow taxes through a mortgage, your lender’s annual escrow analysis will eventually adjust your payment. You can ask for an early reanalysis to speed that up.

Appealing to the Denver County Board of Equalization

If the determination doesn’t go your way, the next step is the Denver County Board of Equalization (CBOE). Your petition must be postmarked or received by July 15 for real property.⁷ This is a fixed calendar deadline, not a rolling window keyed to when you received your determination. The CBOE begins hearing appeals on July 1.⁵

The petition form requires the assessor’s office to fill in parts of it, including the value they assigned, the grounds they relied on, and their written statement refusing to change the value. You add your own statement explaining why you disagree and a specific dollar value you believe is correct.⁷ The hearing is more formal than the assessor-level conversation, but the evidence is the same: comparable sales, condition documentation, and the facts supporting a lower value.

If the CBOE Denies the Appeal

Colorado offers three paths beyond the CBOE, and you have to pick one; you can’t pursue them in parallel.⁵ The Board of Assessment Appeals (BAA) is a state administrative board that holds a fresh hearing and reaches an independent decision; a BAA ruling against you can go to the Colorado Court of Appeals within 49 days. You can also file directly in district court for a full trial on the merits, which is the slowest and most expensive route. Binding arbitration puts the dispute in front of an independent arbitrator whose decision neither side can appeal.

For most residential protests, the process ends at the assessor level or the CBOE. The later options generally make financial sense only when the value gap is large enough to justify the time and professional fees.

Exemptions Worth Checking Before You Protest

Two Colorado exemptions can reduce your bill regardless of the assessed value, and both are frequently missed. They stack with a successful protest, so check them either way.

Senior Homestead Exemption

If you’re at least 65, have owned and lived in your home as your primary residence for at least 10 consecutive years, and the state budget funds it, Colorado exempts 50% of the first $200,000 of actual value.⁸ On a $500,000 home, that removes $100,000 from the taxable value before the assessment rate applies. Applications are due to the Denver Assessor by July 15, with a late window through August 15 (though late filers lose appeal rights for that year).

Disabled Veteran Exemption

Veterans with a service-connected disability rated 100% permanent and total by the U.S. Department of Veterans Affairs qualify for the same 50% exemption on the first $200,000 of actual value.⁹ Veterans with individual unemployability status (rated at least 70% but compensated at the 100% rate) also qualify, and Gold Star spouses are eligible. The exemption applies only to a primary residence.

Doing It Yourself vs. Hiring Help

You don’t need a professional to protest a Denver property tax assessment. The process is built for homeowners, and for a straightforward residential case with a moderate value gap, a well-prepared owner with strong comparables does fine. Property tax consultants typically work on contingency at roughly 25% to 33% of the tax savings they achieve, but they can’t represent you in court if the dispute escalates. Attorneys usually make sense only when the dollar stakes are large or the case involves unusual legal issues like classification or exemption denials. Whoever handles it, the fundamentals are the same: comparable sales from the correct data period, accurate property records, and a specific dollar value you can defend.

1
FindLaw. Colorado Code 39-5-122 – Taxpayers Objections and Protests
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Colorado Department of Local Affairs. Understanding Property Taxes in Colorado
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Colorado General Assembly. Colorado Revised Statutes Title 39 – Taxation
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Justia Law. Colorado Code 39-1-103 – Actual Value Determined – When
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Colorado Department of Local Affairs. Protests and Appeals
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Colorado Department of Local Affairs. Filing Deadlines
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FindLaw. Colorado Code 39-8-106 – Petitions for Relief
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Colorado Department of Local Affairs. Property Tax Exemption for Senior Citizens in Colorado
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Colorado Division of Veterans Affairs. Property Tax Exemption