Colorado Income Tax Calculator

How to Use This Colorado Income Tax Calculator

This Colorado income tax calculator estimates your annual state and federal tax liability for 2025 and 2026. Enter your gross wages, filing status, and any pre-tax deductions above. Colorado applies a flat 4.4% rate to taxable income after subtracting the standard deduction ($16,100 single / $32,200 MFJ in 2026) — no brackets, no phase-outs, no graduation.

This tool focuses on your annual tax picture — ideal for comparing job offers across states, estimating quarterly estimated payments, or planning how much to withhold. For a per-paycheck breakdown, use the Colorado paycheck calculator; to compare Colorado against other states, use the general income tax calculator.

How Colorado's Flat 4.4% Tax Rate Works

Colorado is one of a small group of states with a flat income tax — a single rate applied to all taxable income regardless of how much you earn. The rate was reduced from 4.55% to 4.4% in 2023 and has remained at 4.4% through 2026.

Colorado taxable income is calculated as:

1. Federal AGI — Colorado starts with the same adjusted gross income as your federal return (with minor state-specific modifications).
2. Subtract the Colorado standard deduction — Colorado conforms to the federal standard deduction: $16,100 single, $32,200 married filing jointly, $24,150 head of household for 2026. Colorado taxpayers who itemize deductions may do so using Form DR 0104AD.
3. Apply 4.4% — the flat rate produces Colorado income tax.

The TABOR Refund — Colorado's Unique Mechanism

Colorado's Taxpayer's Bill of Rights (TABOR) is a constitutional provision requiring voter approval for any tax increase and capping state revenue growth to inflation plus population growth. When actual state revenues exceed the TABOR cap, Colorado must refund the surplus to taxpayers.

Recent TABOR refunds have been substantial — averaging $400–$800+ per filer — and are distributed as a credit on Form DR 0104. This means your effective Colorado income tax rate is often lower than 4.4% in years when the TABOR refund applies. The refund amount changes year to year based on revenue collections.

Colorado Standard Deduction and 401(k) Treatment

Colorado's state standard deduction matches the federal amount — a deliberate conformity that simplifies preparation. For 2026: $16,100 (single), $32,200 (married filing jointly), $24,150 (head of household), $16,100 (married filing separately). These are indexed to inflation and increase most years.

Traditional 401(k) and 403(b) contributions reduce Colorado taxable income just as they reduce federal taxable income. A $23,500 contribution saves a Colorado filer $1,034 in Colorado state tax at 4.4% — plus federal savings at the appropriate bracket (22% for most middle-income earners). The total pre-tax benefit on a maxed 401(k) for a typical Colorado filer is roughly $6,200–$6,500 per year.

FICA Taxes — Social Security and Medicare

FICA taxes are federal and apply to every Colorado worker:

• Social Security: 6.2% on wages up to $176,100 (2025) or $184,500 (2026). No further withholding once you hit the wage base.
• Medicare: 1.45% on all wages with no cap.
• Additional Medicare: 0.9% on wages above $200,000 (single) or $250,000 (married jointly) — employee only, no employer match.

Step-by-Step Example — $100,000 Colorado Single Filer (2026)

1. Gross wages: $100,000
2. Federal standard deduction: −$16,100 → federal taxable income: $83,900
3. Federal income tax (10%/12%/22% brackets): ≈ $13,170
4. FICA: $100,000 × 7.65% = $7,650
5. Colorado standard deduction: −$16,100 → CO taxable income: $83,900
6. Colorado income tax: $83,900 × 4.4% ≈ $3,692
7. Total taxes: $13,170 + $7,650 + $3,692 = $24,512
8. Annual net income: $100,000 − $24,512 = $75,488

If a TABOR refund of $800 applies, Colorado tax is effectively $2,892, and annual net income rises to approximately $76,288.

How to Reduce Your Colorado Annual Tax Liability

• Maximize traditional 401(k) contributions — the 2026 limit is $23,500 ($31,000 if age 50+). At a combined 4.4% CO + 22% federal = 26.4% marginal rate, every $1,000 contributed saves $264.
• Contribute to an HSA — $4,300 (self-only) or $8,550 (family) in 2026. Reduces both federal and Colorado taxable income.
• Colorado 529 College Savings Plan — Colorado taxpayers who contribute to the CollegeInvest 529 plan can deduct contributions up to $22,000 per year (single) or $44,000 (joint) from Colorado taxable income. At 4.4%, maxing a 529 saves up to $968–$1,936 per year in Colorado state tax alone.
• Military pay subtraction — active duty military pay is fully exempt from Colorado income tax for Colorado residents on active duty orders, regardless of where income is earned.
• File your return to receive TABOR refunds — file Form DR 0104 even if you expect no balance due; the TABOR refund credit is only issued to those who file.

Tax Disclaimer

This calculator provides estimates for informational purposes only. It is not tax advice. Colorado tax rates, standard deduction amounts, TABOR refund figures, and 529 deduction limits change annually. Federal brackets, FICA wage bases, and standard deduction amounts also change each year. Consult a qualified tax professional or Colorado-licensed CPA for guidance on your specific situation.