Yes. Colorado does have a state income tax, charged at a flat 4.40% rate on the taxable income of residents and on Colorado-source income earned by nonresidents.1Justia Law. Colorado Code Title 39 – Section 39-22-104 There are no graduated brackets. Whether you earn $30,000 or $300,000, the same percentage applies, and the calculation begins with the taxable income figure from your federal return.
The Flat Rate and How It Works
Colorado Revised Statutes 39-22-104 fixes the rate at 4.40%. Voters approved that number through Proposition 121, effective for tax years beginning on or after January 1, 2022.
Because the state calculation starts with your federal taxable income, your federal standard or itemized deduction is already baked into the starting number. Colorado then applies its own additions and subtractions to reach the amount you actually owe.2Department of Revenue – Taxation. Individual Income Tax Guide Common subtractions include contributions to a CollegeInvest tuition savings account and capital gains on qualifying Colorado-source assets held for at least five years. A common addition is interest earned on municipal bonds issued by other states.3Department of Revenue – Taxation. DR 0104 – Individual Income Tax Return After the 4.40% rate is applied, any credits you qualify for come off the top to reach your final tax liability.
Colorado taxpayers report all of this on Form DR 0104. Part-year residents and nonresidents also complete Form DR 0104PN.
Who Has to File
You must file a Colorado return if you are required to file a federal return, or you owe Colorado tax for the year, and you fall into one of these categories:4Department of Revenue – Taxation. Individual Income Tax Filing Requirements
- Full-year residents who maintained a home in Colorado for the entire year.
- Part-year residents who moved in or out during the year and had taxable income while living here.
- Nonresidents who earned income from Colorado sources, such as wages for work performed in the state or rental income from Colorado property.
Who Counts as a Resident
You are a Colorado resident if you are domiciled here — Colorado is the place you consider your permanent home and intend to return to whenever you are away. The Department of Revenue weighs factors like voter registration, vehicle registration, driver’s license, school enrollment, and where your spouse and children live.
Domicile is not the only path in. If you maintain a permanent place to live in Colorado and spend more than six months of the tax year in the state (in total, not necessarily consecutively), you are classified as a resident.5Department of Revenue – Taxation. Income Tax Topics – Part-Year Residents and Nonresidents
Active-Duty Military
Servicemembers remain residents of whatever state they lived in when they entered service, unless they formally change legal residence through their base personnel office. A nonresident servicemember stationed in Colorado owes no Colorado tax on military wages, but any non-military Colorado income still has to be reported.6Department of Revenue – Taxation. Active Duty Servicemembers A Colorado-resident servicemember stationed outside the United States for at least 305 days of the tax year may file as a nonresident, and an accompanying spouse can do the same. A military spouse who moved to Colorado solely on military orders may exclude their own wages from Colorado tax.
TABOR Refunds
Colorado’s Taxpayer’s Bill of Rights, approved by voters in 1992, caps the revenue the state can keep each year. When collections exceed the cap, the excess is refunded to taxpayers.7Department of Revenue – Taxation. TABOR You claim the refund on your Colorado income tax return or through the Property Tax/Rent/Heat Rebate application, and it is combined with any other refund you are owed rather than paid as a separate check.
In some years the state also applies a temporary rate reduction as part of the TABOR mechanism. For the 2024 tax year, the rate was temporarily reduced from 4.40% to 4.25%, and a separate sales tax refund was available on top of that reduction. For tax year 2025, the sales tax refund ranged from $19 to $59 for single filers and $38 to $118 for joint filers, depending on adjusted gross income. Amounts shift annually, so check the Department of Revenue’s TABOR page for the figures that apply the year you file.
Retirement Income Breaks
If you are 65 or older at the end of the tax year, you can subtract the full amount of Social Security benefits included in your federal taxable income. In practice, most retirees 65 and older pay no Colorado tax on Social Security.8Department of Revenue – Taxation. Income Tax Topics – Social Security, Pensions and Annuities
At ages 55 to 64, you can still subtract the full taxable amount of Social Security if your adjusted gross income is at or below $75,000 (single) or $95,000 (joint). Above those thresholds, the subtraction is capped at $20,000.
Taxpayers under 65 can subtract up to $20,000 of pension or annuity income included in federal taxable income.9Department of Revenue – Taxation. Individual Income Tax – Information for Retirees Any Social Security subtraction you claim reduces what you can subtract for other pension or annuity income under this limit.
Credits Worth Knowing
Colorado offers its own earned income tax credit calculated as a percentage of the federal EITC. For tax year 2026 and later, the state credit is 25% of the federal amount, and taxpayers who cannot claim the federal credit may still qualify for the state version by filing Form DR 0104TN.10Department of Revenue – Taxation. Earned Income Tax Credit
Colorado also provides a state child tax credit for each qualifying child under age 6, with the amount tiered by filing status and AGI. For tax year 2025, credits ranged from $200 to $1,200 per child, phasing down as income rises and cutting off at $77,000 for single filers and $87,000 for joint filers.11Department of Revenue – Taxation. Income Tax Topics – Child Tax Credit Thresholds adjust each year.
Deadlines, Extensions, and Payments
The annual filing deadline is April 15. When that date falls on a weekend or holiday, the deadline shifts to the next business day.12Department of Revenue – Taxation. Individual Income Tax – Due Dates and Filing Extension You can file electronically through Revenue Online, the state’s free e-file portal, or use commercial software, a paid preparer, or a paper return.13Department of Revenue – Taxation. File Individual Income Tax Online
Every Colorado taxpayer gets an automatic six-month filing extension without submitting any form. You just need to file by October 15. The extension covers filing only, not payment: to avoid penalties, at least 90% of your total tax liability must be paid by April 15.
If your Colorado tax liability after withholding and credits will exceed $1,000, you have to make quarterly estimated payments using Form DR 0104EP or Revenue Online. For 2026, the due dates are April 15, June 15, September 15, and January 15, 2027.14Department of Revenue – Taxation. Colorado Estimated Income Tax Payment Form DR 0104EP This most often applies to self-employed workers, freelancers, and people with significant investment income that has no tax withheld.
After filing, you can track your refund through the Department of Revenue’s online tool. Electronic returns are typically processed in three to five weeks, and paper returns can take up to three months.15Department of Revenue – Taxation. Refund
Penalties for Filing or Paying Late
A late filing or late payment triggers a penalty equal to the greater of $5 or 5% of the unpaid tax, plus an additional 0.5% for each full or partial month the balance stays unpaid. The total is capped at 12% of the amount owed.16Department of Revenue – Taxation. Tax Topics – Penalties and Interest
Interest runs on top of the penalty. For calendar year 2026, the standard rate on underpayments is 11%, with a discounted 8% rate available in certain situations. Missing quarterly estimated payments can also draw a separate underpayment penalty, so keeping up during the year avoids compounding charges.
A Note on City Occupational Taxes
Some Colorado cities layer a small monthly occupational privilege tax on top of state and federal withholding. It is not a state income tax, but it shows up on pay stubs and often surprises new workers. In Denver, employees who earn at least $500 in a calendar month pay $5.75 per month, typically withheld by the employer.17City and County of Denver. Occupational Privilege Taxes Aurora and several other cities impose similar taxes with their own thresholds and amounts.