How the Czechia čistá mzda calculator is verified
Inputs
| Input | Field | Type |
|---|---|---|
| Hrubá mzda / měsíc (CZK) | grossMonthly | number |
| Počet dětí | children | number |
The formula
Each derived value below is computed by the Valem engine from the expression shown, in this order. Nothing else runs — there is no hidden code path.
| Derived value | Field | Formula (JSONata) |
|---|---|---|
| Sociální (7,1%) | social | $round(grossMonthly * $const.socialRate, 2) |
| Zdravotní (4,5%) | health | $round(grossMonthly * $const.healthRate, 2) |
| Tax Gross | taxGross | ($g := grossMonthly; $round($g <= $const.threshold23 ? $g * 0.15 : $const.threshold23 * 0.15 + ($g - $const.threshold23) * 0.23, 2)) |
| Child Credit | childCredit | ($c := children; $c <= 0 ? 0 : $c = 1 ? 1267 : $c = 2 ? 3127 : 3127 + ($c - 2) * 2320) |
| Daň po slevách | taxNet | ($a := taxGross - $const.taxpayerCredit; $a := $a > 0 ? $a : 0; $round($a - childCredit, 2)) |
| Čistá / měsíc | netMonthly | $round(grossMonthly - social - health - taxNet, 2) |
Rates and thresholds
The expressions above read these as $const. They are the figures the annual refresh replaces, so they live as data rather than being written into the formulas — which is what makes a year-on-year change a one-line diff instead of an edit to arithmetic.
| Constant | Value |
|---|---|
socialRate | 0.071 |
healthRate | 0.045 |
taxpayerCredit | 2570 |
threshold23 | 146901 |
Test vectors (2)
Every case is executed against this model on each build, by the Java engine and independently by a JavaScript one. A mismatch of a single cent fails the build, so the page cannot ship advertising a figure the model no longer produces.
Case 1 — S1 45,000 CZK single
given grossMonthly | 45000 |
|---|---|
given children | 0 |
expect social | 3195 |
expect health | 2025 |
expect taxNet | 4180 |
expect netMonthly | 35600 |
Case 2 — S2 45,000 CZK with 2 children
given grossMonthly | 45000 |
|---|---|
given children | 2 |
expect childCredit | 3127 |
expect taxNet | 1053 |
expect netMonthly | 38727 |
Sources
- Finanční správa · checked 2026-08-02
- ČSSZ · checked 2026-08-02
Check it yourself — and reuse it
The whole model as JSON — inputs, outputs, formulas, vectors and sources in one re-runnable document.
This model is published under CC BY 4.0: use it, adapt it, build on it, with attribution. The licence covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds are law, and nobody licenses those; the sources above are where they come from.
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