Colorado (CO) Self Employment Tax Calculator

Colorado has a flat 4.4% income tax applied to federal taxable income. For self-employed people, that means your net profit minus the deductible half of SE tax minus the federal standard deduction ($16,100 single / $32,200 MFJ for 2026) forms the base. Colorado adopted federal taxable income as its starting point, so the federal standard deduction effectively reduces CO tax too. Source: Colorado Department of Revenue.

Colorado conforms closely to federal definitions of income and deductions by starting from Form 1040 Line 15 (federal taxable income). This means the federal standard deduction, the deductible half of SE tax, and QBI deductions all reduce Colorado taxable income automatically — no separate Colorado standard deduction is needed.

Self-employment (SE) tax is the Social Security and Medicare tax paid by freelancers, 1099 contractors, and sole proprietors. Employees split these costs with their employer (7.65% each); when you work for yourself you pay both halves — 15.3% total — on 92.35% of your net profit. It is separate from, and on top of, federal and state income tax.

Yes. In addition to federal SE tax, Colorado taxes self-employment net profit as ordinary income. This calculator shows both: the federal SE tax (Social Security + Medicare) and the estimated Colorado state income tax side by side, so you can see your true combined tax bill.

Yes — from federal income tax. You can deduct one half of your Social Security and Medicare SE tax as an above-the-line adjustment to income on Form 1040. This deductible half also reduces your federal AGI, which in turn reduces your state taxable income in most states (except Pennsylvania, which taxes gross compensation regardless).

SE tax is based on net profit (gross revenue minus business expenses), so every legitimate business deduction reduces both your SE tax and your state income tax. Common deductions include home-office use ($5/sqft simplified method), equipment and software (Section 179), business mileage, and professional services. The standard deduction and QBI deduction reduce income tax only — not SE tax.

SE tax is paid through quarterly estimated payments (Form 1040-ES), due April 15, June 16, September 15, and January 15 for the prior year's fourth quarter. If you expect to owe $1,000 or more in federal tax after withholding, you generally must pay quarterly to avoid the IRS underpayment penalty. Most states that tax SE income have parallel quarterly estimated payment requirements.