When you’re self-employed, no one withholds tax on your behalf — you set money aside and pay it yourself, typically in quarterly instalments. This calculator estimates what one quarterly payment might look like, based on your profit and the rates you provide. No rates are hardcoded: you enter what applies to your situation, and the calculator does the arithmetic. It is a planning estimate only, not tax advice.
How the quarterly estimate is calculated
The calculator takes three numbers you supply and runs a straightforward calculation:
Self-employment tax = Net profit × SE tax rate Income tax = Net profit × Income tax rate Total annual tax = Self-employment tax + Income tax Quarterly payment = Total annual tax ÷ 4
That’s the complete formula. You provide the rates; the calculator multiplies and divides. The result is a rough estimate of what to set aside every three months so you’re not caught off guard at year end.
Why you enter the rates yourself
Tax rates change year to year, and they differ by country and region. A hardcoded rate would silently become wrong over time, giving you a false sense of accuracy. By entering your own rates, the estimate is always as current as the information you bring to it. If a rate changes, you update the input — the calculator itself never becomes outdated.
A worked example
Say your estimated annual net profit is $80,000, your SE tax rate is 15.3%, and your estimated effective income tax rate is 12%.
Self-employment tax: $80,000 × 15.3% = $12,240 Income tax: $80,000 × 12% = $9,600 Total annual tax: $12,240 + $9,600 = $21,840 Quarterly payment: $21,840 ÷ 4 = $5,460
Change any input to test different scenarios — a higher income, a different tax rate, or both.
The most common mistake
The most common error freelancers make is budgeting only for income tax and forgetting self-employment or payroll tax entirely. If you’ve only ever been an employee, your employer paid part of this on your behalf and you never saw it. As a self-employed person, you pay the full amount yourself. Including both layers in this calculator is the whole point — so you can see each piece and plan for both.
What else affects your actual quarterly payment
This calculator simplifies a genuinely complex calculation. Your real quarterly payment may differ because of deductions, tax credits, retirement contributions, regional rules, income thresholds and safe-harbour provisions. Payment due dates also vary by jurisdiction. None of these are modelled here. Use this estimate as a starting point, and confirm your actual obligation with a licensed tax professional before you pay.