Tax Bracket Calculator for Colorado (CO) — Free Calculator

Colorado Tax Brackets (2026)

Colorado uses a flat income tax system with a top marginal rate of 4.40% flat.

Colorado Bracket Structure

Flat 4.40% on all Colorado taxable income (reduced from 4.55% in 2023 via TABOR refund mechanism)

Colorado uses a flat income tax tied to Colorado taxable income, which starts with federal AGI. The rate can temporarily drop further under TABOR (Taxpayer's Bill of Rights) when state revenues exceed the cap.

Federal Tax Brackets Still Apply to Colorado Residents

Regardless of Colorado's state tax rules, all residents pay federal income tax. Federal brackets for 2024 range from 10% (on income up to $11,600 for single filers) to 37% (on income over $609,350). Your effective federal rate is typically well below the top marginal rate due to the graduated bracket structure.

Effective vs. Marginal Rate in Colorado

Your marginal rate is the rate on your last dollar of income. Your effective rate is your total tax divided by total income. For Colorado residents the marginal rate can reach 4.40% flat but most filers pay a lower effective rate. The median household income in Colorado is $80,630.

Data: Tax Foundation (2024), IRS Statistics of Income, US Census Bureau ACS 2023. Updated 2024–2025. Figures reflect state averages — consult a licensed CPA for personalized tax advice.

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Frequently Asked Questions

What tax brackets apply to Colorado residents?

Colorado has a flat income tax system. Flat 4.40% on all Colorado taxable income (reduced from 4.55% in 2023 via TABOR refund mechanism). Federal brackets also apply on top of the state tax.

What is the difference between marginal and effective tax rate in Colorado?

Your marginal rate is the rate on your highest dollar of income. Your effective rate is your total tax burden divided by total income. In Colorado, even if the top marginal rate is 4.40% flat, most residents pay a lower effective rate because lower income portions are taxed at lower brackets.

Does Colorado have different tax brackets for married filers?

Yes, Colorado typically has different bracket thresholds for single vs. married filing jointly filers. Married joint filers often have brackets approximately twice as wide, reducing the marriage penalty. Check the Colorado Department of Revenue for current bracket tables.

How does this tax bracket calculator work for Colorado?

Enter your income and filing status. The calculator applies both federal and Colorado state tax brackets to show your marginal rate, effective rate, and total estimated tax. Colorado's flat rate of up to 4.40% flat is applied to your state taxable income.