The federal part applies everywhere
Wherever you live, self-employment income carries two federal taxes. The first is self-employment tax at 15.3% of net earnings, covering Social Security and Medicare — the portions an employer would normally split with you. The second is federal income tax, calculated on your profit after the standard deduction and the deductible half of your self-employment tax.
This part does not change based on your state. A freelancer in Colorado and a freelancer anywhere else owe the same federal self-employment tax on the same profit. The self-employment tax calculator works out that figure.
What Colorado adds
A state layer on top of the federal one. Because the rate is flat, your state liability scales directly with your taxable income: the same percentage applies whether you had a strong year or a lean one, which makes estimating it straightforward once you know the rate. Most states begin from a federal income figure, which means the deductions that lower your federal tax generally lower your state tax too.
Colorado applies a single flat rate to taxable income, calculated from your federal taxable income as a starting point.
Quarterly payments in Colorado
Most states that levy an income tax also expect estimated payments through the year from people whose income isn't withheld, and Colorado generally follows that pattern. That means two sets of quarterly payments: one to the IRS and one to the state, on their own schedule and through their own payment system. Confirm the current thresholds and due dates with the Colorado department of revenue, since state deadlines don't always line up with the federal ones.
The quarterly estimated tax calculator handles the federal side, and the deadlines guide lists the federal due dates.
Deductions work the same way
Business expenses reduce your net profit, which lowers your federal self-employment tax and federal income tax and generally your Colorado state tax as well, since most states start from a federal income figure. Software, equipment, a home office, mileage, and professional fees commonly qualify. The write-off guide covers what usually counts.