Colorado (CO) Freelance Effective Tax Rate Calculator

Your effective tax rate is the total tax you owe (SE tax + federal income tax + state income tax) divided by your total net self-employment income. This is a blended average across all dollars earned, not the rate on the next dollar. The combined marginal rate on the next dollar is higher than the effective rate because earlier dollars are taxed at lower bracket rates.

Your marginal rate is the tax you pay on the next dollar earned. Your effective rate is the average rate across all dollars. Always plan quarterly estimated tax using the marginal rate on incremental income, but use the effective rate to understand your overall tax burden and what to set aside.

Set aside your all-in effective rate as a percentage of each payment you receive. Add a 5% buffer for unexpected income increases. Quarterly estimated tax payments are due April 15, June 16, September 15, and January 15. The IRS safe-harbor rule: pay 100% of the prior year's tax liability (110% if AGI was above $150,000) to avoid underpayment penalties.

Colorado taxes federal taxable income at a flat 4.4% rate for 2026. There is no separate Colorado standard deduction; the calculator uses the federal standard deduction already applied to the federal taxable income figure. At $80,000 net profit (single), the Colorado component adds roughly 4.4% of federal taxable income to the all-in effective rate.

Colorado's flat 4.4% rate makes state tax easy to plan for: any dollar of federal taxable income reduction (from retirement contributions, home office, etc.) saves exactly 4.4 cents in Colorado tax. This predictability is useful for quarterly estimated tax calculations. Colorado uses the federal taxable income starting point, so federal deductions cascade directly into Colorado savings.