How the estimate works
The calculation steps, sources, and scope behind Czechfolio’s 2026 freelancer tax calculator.
Rules last checked: 4 September 2026
1. Revenue and expenses
The standard estimate starts with annual invoiced revenue. It deducts either your entered actual expenses or the statutory lump-sum allowance for the selected activity. The allowance has an annual cap; it is not a measurement of your real business costs.
2. Income tax and credits
Eligible deductions reduce the taxable base, which is rounded down to the nearest 100 Kč. The calculator applies 15% up to 1 762 812 Kč and 23% to the portion above that threshold. It then applies the basic taxpayer credit and selected eligible credits. Child credits can produce a refundable bonus when the income condition is met.
3. Social and health insurance
The standard calculation uses 55% of profit as the social-insurance assessment base and 50% as the health-insurance assessment base, subject to the modeled minimums, participation threshold, and social-insurance maximum. Annual liability is calculated separately from rounded monthly advances.
4. The flat-tax comparison
The calculator compares the standard estimate with the lowest flat-tax band available for the entered revenue and selected activity category. The comparison assumes all self-employment revenue belongs to that category. Fixed monthly payments replace the separate standard-regime calculation; credits and deductions do not reduce those fixed payments. Revenue and activity alone do not establish eligibility, so use the eligibility check and official guidance.
5. Cash retained
Cash retained is revenue minus income tax and mandatory insurance, plus any modeled refundable child tax bonus. Actual business costs have not been subtracted from this figure, including when actual expenses are used to calculate the taxable profit. It is not your accounting profit or a complete household-income estimate.
Assumptions and limitations
The estimate assumes a Czech tax resident, a full calendar year of activity, and one self-employment income category. Primary activity uses the established-freelancer minimum. Secondary activity estimates only self-employment income and does not reconcile salary or credits already used through payroll.
Partial-year activity, foreign income, VAT, multiple income categories, carried tax losses, donations, disability-related credits, working-pensioner discounts, voluntary sickness insurance, and reduced minimums for qualifying new freelancers require separate review. These estimates do not constitute professional tax advice.
Sources and maintenance
The calculator’s rates and thresholds are stored together by tax year. The documented maintenance process calls for checking official guidance, updating the displayed verification date, and running calculation checks covering thresholds, rounding, credits, and insurance limits. The date records the latest documented rules check; it is not a claim of professional certification.