Colorado's income tax rate is a flat 4.40 percent on all taxable income

Colorado uses a flat tax system, meaning everyone pays the same percentage of their taxable income to the state, regardless of how much they earn. That rate is 4.40 percent as of the 2024 tax year. This is lower than the federal income tax, which uses brackets that increase with income, but Colorado applies the same 4.40 percent to a teacher earning $40,000 and a software engineer earning $200,000.

The 4.40 percent rate applies to your taxable income — not your total earnings. Taxable income is what remains after you subtract deductions and exemptions. Colorado allows you to claim the standard deduction (which varies by filing status) or itemize deductions, just as you do on your federal return. You calculate your federal taxable income first, then explore Colorado's 4.40 percent to that same amount.

Key Takeaways

  • Colorado's flat tax rate of 4.40 percent applies to all residents and applies to the same taxable income you report to the federal government.
  • The flat rate means you pay the same percentage whether you earn $30,000 or $300,000, unlike federal brackets that increase with income.
  • You can claim the standard deduction or itemize deductions on your Colorado return, which reduces the income subject to the 4.40 percent tax.
  • Colorado taxes wages, self-employment income, investment income, and retirement distributions, though some retirement income has special rules.

How Colorado calculates your taxable income

Start with your federal adjusted gross income (AGI) — the number you report on line 11 of your federal Form 1040. Colorado uses that as the starting point for state taxable income. From there, you can claim either the standard deduction or itemized deductions, just as you do federally. The standard deduction for Colorado varies: for the 2024 tax year, it is $3,950 for single filers, $7,900 for married filing jointly, and $5,900 for head of household.

After you subtract your deduction, you arrive at Colorado taxable income. Multiply that number by 0.044 (the 4.40 percent rate) to find your state income tax before credits. Colorado offers several tax credits — such as the child dependent credit and the earned income tax credit — that reduce your final tax bill. These credits are subtracted from your tax after it is calculated, not from your income before.

What types of income Colorado taxes

Colorado taxes most forms of income: wages from employment, self-employment income, interest, dividends, capital gains, rental income, and distributions from retirement accounts. If you receive income, Colorado expects to see it reported on your state return unless a specific exemption applies.

Some retirement income has special treatment. Pension income and distributions from may have access to retirement plans (like traditional IRAs and 401(k)s) are generally taxable at the 4.40 percent rate, but Colorado allows a pension exemption for certain taxpayers. If you are age 55 or older and retired, you may exclude up to $24,000 of pension and retirement plan distributions from your taxable income. Military retirement pay also receives special consideration. Social Security benefits are not taxed by Colorado, even though they are taxable at the federal level.

Colorado tax brackets do not explore — everyone pays the same rate

Unlike the federal system, Colorado has no tax brackets. The federal government taxes your first $11,000 at 10 percent, your next portion at 12 percent, and so on, with rates climbing as your income rises. Colorado ignores that structure entirely. Your first dollar of taxable income is taxed at 4.40 percent, and your last dollar is also taxed at 4.40 percent.

This simplifies the math but means high earners pay a smaller percentage of their total income in state tax than they do federally. A person earning $50,000 in taxable income pays $2,200 in Colorado state tax. A person earning $500,000 in taxable income pays $22,000 — the same rate applied to a larger number, with no increase in the percentage.

When and how to pay Colorado income tax

If you are an employee, your employer withholds Colorado income tax from your paycheck based on a W-4 form you complete. The withholding is sent to the state on your employer's schedule. If you are self-employed or have income not subject to withholding, you may need to make estimated tax payments four times per year — on April 15, June 15, September 15, and January 15 of the following year.

You file your Colorado income tax return by April 15 each year (or the next business day if April 15 falls on a weekend). You can file electronically through the Colorado Department of Revenue website or by mail using Form 104, the Colorado Individual Income Tax Return. If you owe money, you pay it with your return. If you overpaid through withholding or estimated payments, you receive a refund.

How Colorado's rate compares to other states

Colorado's 4.40 percent flat rate is lower than the top federal rate (37 percent) and lower than the top rates in many neighboring states. Wyoming and Nevada have no state income tax at all. New Mexico's top rate is 5.9 percent, Utah's is 4.65 percent, and Kansas's is 5.7 percent. However, some states with higher income tax rates offer more deductions or credits that reduce the effective tax paid.

The 4.40 percent rate has been in place since 2000. Colorado voters approved a constitutional amendment that year that capped the state income tax rate at 4.63 percent and required the rate to decrease if state revenue exceeded certain thresholds. The rate has since dropped to 4.40 percent due to those revenue triggers, though it can increase back toward the 4.63 percent cap if revenue falls short.

Special situations and deductions

If you are a Colorado resident, you owe state income tax on all income, regardless of where you earned it. If you worked in another state or country, you may owe tax to both Colorado and that other jurisdiction, though you can often claim a credit for taxes paid elsewhere to avoid double taxation.

Colorado residents who move out of state during the year owe tax only on income earned while they were residents. If you move into Colorado mid-year, you owe tax only on income earned after you became a resident. Non-residents who earned income in Colorado may also owe Colorado tax on that income, even if they live elsewhere.

Frequently Asked Questions

Does Colorado tax Social Security?

No. Colorado does not tax Social Security benefits, even though the federal government may. This is one of the few income sources Colorado excludes from taxation. If Social Security is your only income, you will have no Colorado state income tax liability.

What is the difference between Colorado's flat tax and federal brackets?

Colorado taxes all income at 4.40 percent. The federal government uses brackets: 10 percent on the first portion, 12 percent on the next, and so on, up to 37 percent on the highest earners. This means a high earner in Colorado pays a lower percentage to the state than to the federal government, while a low earner pays the same 4.40 percent as everyone else.

Can I deduct federal income tax from my Colorado return?

No. Colorado does not allow you to deduct federal income tax paid. However, if you itemize deductions on your federal return, you can deduct state income tax paid (up to $10,000 combined with other state and local taxes) on your federal return, which indirectly reduces your federal bill.

Do I owe Colorado tax if I work remotely for an out-of-state company?

Yes, if you are a Colorado resident. You owe Colorado income tax on all income you earn, regardless of where your employer is located or where you physically work. Your employer may withhold based on your work location, so you may need to adjust your withholding or make estimated payments to avoid owing at tax time.

What happens if I move to Colorado mid-year?

You owe Colorado income tax only on income earned after you became a resident. You will file a part-year resident return and report only the income earned during the months you lived in Colorado. You may also owe tax to your previous state on income earned there, depending on that state's rules.