What is the self-employment tax rate?

Federal self-employment tax is 15.3% — 12.4% for Social Security plus 2.9% for Medicare. The Social Security portion applies only up to the annual wage base ($168,600 for 2024); above that, only the 2.9% Medicare portion continues. It is calculated on 92.35% of your net profit.

How does Colorado tax self-employment income?

Colorado does not have a separate self-employment tax. Your net self-employment profit flows into your Colorado taxable income and is taxed at the flat 4.40% rate, after the federal deduction for one-half of your SE tax reduces the income that reaches your return.

What is the half-SE-tax deduction?

You can deduct one-half of your federal self-employment tax as an above-the-line adjustment to income. This lowers the income base that both federal income tax and Colorado's flat tax apply to, partially offsetting the cost of paying both halves of FICA yourself.

Do I need to make quarterly estimated payments in Colorado?

Generally yes. Self-employed people usually owe both federal and Colorado estimated taxes four times a year because nothing is withheld for them. This calculator divides your combined SE plus Colorado tax by four as a rough quarterly target; adjust for your income tax bracket and credits.

Does this include my federal income tax bracket?

No. This tool isolates self-employment tax plus the Colorado flat tax on SE income so you can budget those specific liabilities. Your full federal income tax depends on all your income, deductions, and bracket, which a complete return or tax software will calculate.

Colorado Self-Employment Tax Calculator

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The Colorado self-employment tax calculator stacks the 15.3% federal SE tax on top of Colorado’s flat 4.40% income tax, accounts for the deductible half of SE tax, and estimates your quarterly payments — so freelancers and sole proprietors can budget accurately.

How it works

Self-employment income is taxed in two layers:

Federal SE tax (Schedule SE). Your net profit is multiplied by 0.9235 to get net earnings. The Social Security portion (12.4%) applies up to the wage base; the Medicare portion (2.9%) applies to all net earnings, for a combined 15.3% below the cap.
Half-SE-tax deduction. One-half of the SE tax is deducted from the income that reaches your income-tax calculation.
Colorado state tax. Colorado applies its flat 4.40% rate to your SE income after the half-SE-tax adjustment.

Add the two layers together for your total tax on self-employment income, then divide by four for a rough quarterly estimate.

Worked example

A freelancer with $80,000 net profit and no W-2 wages:

Net earnings: $80,000 × 0.9235 = $73,880
SE tax: $73,880 × 15.3% ≈ $11,303
Half-SE deduction: ≈ $5,651
Colorado base: $80,000 − $5,651 = $74,349
Colorado tax: $74,349 × 4.40% ≈ $3,271
Total: $11,303 + $3,271 ≈ $14,574 → about $3,644 per quarter.

Notes and tips

If you also hold a W-2 job, enter those Social Security wages so the tool caps the SS portion correctly and avoids over-charging above the wage base.
The half-SE-tax deduction only reduces income tax, not the SE tax itself — you still pay the full 15.3% to the IRS.
This isolates SE and Colorado tax. For your full federal bill, combine it with your income-tax bracket using complete tax software or a preparer.