Colorado has a state income tax, and it applies to most residents and workers

Yes, Colorado collects state income tax. The state tax rate is a flat 4.40% on federal taxable income, meaning everyone pays the same percentage regardless of how much they earn. This rate applies to wages, self-employment income, investment gains, and other taxable sources. Colorado is one of 41 states that tax income; only nine states have no income tax at all.

The 4.40% rate has been in place since 2022, when Colorado voters approved a temporary rate reduction. Before that, the rate was 4.63%. The rate can change if voters approve a new measure or if the legislature passes a law, but any increase requires voter approval under Colorado's Taxpayer Bill of Rights (TABOR).

If you work in Colorado or live there, you will owe state income tax on your earnings. If you work in Colorado but live in another state, you may owe Colorado tax on wages earned in the state, though you can usually claim a credit on your home state's return to avoid double taxation.

Key Takeaways

  • Colorado's state income tax rate is 4.40% on federal taxable income, applied equally to all residents and workers.
  • You must file a Colorado state return if you earned income in the state or lived there for part of the year, even if you owe no tax.
  • Colorado allows a standard deduction and personal exemptions that reduce the income subject to tax, similar to the federal system.
  • If you moved to or from Colorado during the year, you file as a part-year resident and pay tax only on income earned while living in the state.
  • Self-employed people and business owners in Colorado owe state income tax on net business income after deducting business expenses.

Who has to file a Colorado state return

You must file a Colorado state return if you lived in Colorado for any part of the tax year and had income above the filing threshold. The threshold depends on your age and filing status. For the 2023 tax year, a single person under 65 must file if they had more than $14,600 in income; a married couple filing jointly must file if they had more than $29,200. These thresholds increase slightly each year for inflation.

Even if your income falls below the threshold, you should file if you had Colorado income tax withheld from your paychecks. Filing allows you to claim a refund of that overpayment. You must also file if you owe Colorado tax, even if you do not owe federal tax.

Part-year residents — people who moved to or from Colorado during the year — file as part-year residents and pay Colorado tax only on income earned while living in the state. You will need to show the dates you moved in or out.

Colorado's standard deduction and personal exemptions

Colorado allows a standard deduction that reduces your taxable income before the 4.40% rate is applied. For 2023, the standard deduction is $14,600 for single filers and $29,200 for married couples filing jointly. These amounts are adjusted each year. You can use the standard deduction or itemize deductions if itemizing produces a larger deduction, though most Colorado taxpayers use the standard deduction.

Colorado also allows personal exemptions of $4,850 per person for 2023 (adjusted annually). If you are married filing jointly, you claim two exemptions — one for yourself and one for your spouse. You also claim an exemption for each dependent child or other may have access to dependent. These exemptions further reduce your taxable income.

The combination of the standard deduction and personal exemptions means many Colorado residents owe little or no state tax. For example, a married couple with two children and $60,000 in income would subtract $29,200 (standard deduction) plus $19,400 (four exemptions at $4,850 each), leaving only $11,400 subject to the 4.40% rate — roughly $502 in state tax.

How Colorado income tax is withheld from paychecks

If you work for an employer in Colorado, your employer withholds Colorado state income tax from each paycheck based on the Colorado W-5 form you complete when hired. This form tells your employer how much to withhold based on your income, filing status, and number of dependents. The withholding is an estimate; you may owe more or receive a refund when you file your return.

You can adjust your withholding during the year by submitting a new W-5 to your employer. If you expect to owe tax or want a larger refund, you can claim fewer exemptions on the form to increase withholding, or claim more exemptions to decrease it. Many people adjust their withholding after a major life change — marriage, divorce, a second job, or a child born.

Self-employed people do not have an employer to withhold tax, so they must pay estimated tax four times per year. Colorado estimated tax payments are due on the same dates as federal estimated payments: April 15, June 15, September 15, and January 15 of the following year. You can pay online through the Colorado Department of Revenue website.

Self-employment income and business taxes in Colorado

If you are self-employed or own a business in Colorado, you owe state income tax on your net business income — that is, revenue minus business expenses. You calculate net income the same way you do for federal taxes: on Schedule C (for sole proprietors) or Schedule E (for rental income). Colorado then applies the 4.40% rate to that net income.

You do not pay a separate Colorado self-employment tax. However, you do owe federal self-employment tax (Social Security and Medicare), which is calculated on your net earnings. Colorado state tax is separate and is calculated on the same net income figure.

If you operate as an S-corporation, partnership, or LLC, Colorado taxes the income that passes through to you personally. The business entity itself does not pay Colorado income tax; instead, the owners pay tax on their share of the income on their individual returns. This is the same structure as federal taxation.

Filing your Colorado return and where to send it

Colorado uses federal taxable income as the starting point for state tax. You calculate your federal return first (Form 1040), then use that information to complete the Colorado return (Form 104). Most people file both returns at the same time, either on paper or electronically.

You can file your Colorado return electronically through the Colorado Department of Revenue website or through tax software that supports Colorado returns. Paper returns are mailed to the Colorado Department of Revenue in Denver. The important date is the same as the federal important date: April 15 of the following year, or the next business day if April 15 falls on a weekend or holiday.

If you need more time, you can request an extension by filing Form 104-EXT. An extension gives you until October 15 to file, but it does not extend the important date to pay any tax you owe. If you owe tax and do not pay by April 15, you will owe interest and penalties on the unpaid amount, even if you filed an extension.

Credits and deductions unique to Colorado

Colorado offers several tax credits that reduce your state tax bill. The Colorado Child Care Expense Credit allows you to claim a percentage of child care costs if you paid for care so you could work. The Earned Income Tax Credit (EITC) is available to lower-income workers and is calculated based on federal EITC rules but may differ slightly in amount.

Colorado also allows a Property Tax/Rent/Heat Credit for low-income seniors and disabled people who own a home or rent. This credit reimburses a portion of property taxes, rent, or home heating costs. The amount depends on your income and the amount you paid.

If you paid income tax to another state on income you also reported to Colorado, you can claim a credit for taxes paid to other states. This prevents you from paying tax twice on the same income. The credit is limited to the lesser of the tax you paid to the other state or the Colorado tax on that income.

Frequently Asked Questions

Do I have to file a Colorado return if I only worked there part of the year?

Yes, if you earned income in Colorado during any part of the tax year, you must file as a part-year resident. You pay Colorado tax only on the income you earned while living in the state. You will need to show the dates you moved in and out of Colorado on your return.

What if I moved out of Colorado — do I still owe state tax?

You owe Colorado tax only on income earned while you lived in the state. Once you move out, you file as a part-year resident for that year and pay tax only on income earned before your move date. After you leave, you owe no Colorado tax on future income earned outside the state.

Can I claim Colorado tax paid to another state as a credit?

Yes. If you lived in Colorado but earned income in another state and paid tax to that state, you can claim a credit on your Colorado return. The credit is limited to the smaller of the tax you paid to the other state or the Colorado tax on that income, preventing double taxation.

Is Colorado income tax deductible on my federal return?

Yes, if you itemize deductions on your federal return. Colorado state income tax is deductible as a state and local tax (SALT) on Schedule A. However, the total SALT deduction is capped at $10,000 per year, so high-income earners in high-tax states may not be able to deduct all their state taxes.

What happens if I do not file a Colorado return when I should have?

The Colorado Department of Revenue can assess penalties and interest on unpaid tax. If you owe tax and do not file, penalties begin to accrue when ready. If you filed late but did not owe tax, penalties are usually smaller or waived. Filing as soon as you can, even if late, is better than not filing at all.