How the Poland wynagrodzenie netto calculator is verified
Inputs
| Input | Field | Type |
|---|---|---|
| Wynagrodzenie brutto / miesiąc (PLN) | grossMonthly | number |
| Ulga dla młodych (<26 lat) | under26 | boolean |
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) |
|---|---|---|
| ZUS | zus | $round(grossMonthly * $const.zusRate, 2) |
| After Zus | afterZus | $round(grossMonthly - zus, 2) |
| Składka zdrowotna | health | $round(afterZus * $const.healthRate, 2) |
| Pit Base | pitBase | ($b := afterZus - $const.monthlyCosts; $round($b > 0 ? $b : 0, 2)) |
| PIT | pit | (under26 ? 0 : ($p := pitBase * 0.12 - $const.monthlyCredit; $round($p > 0 ? $p : 0, 2))) |
| Netto / miesiąc | netMonthly | $round(grossMonthly - zus - health - pit, 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 |
|---|---|
zusRate | 0.1371 |
healthRate | 0.09 |
monthlyCosts | 250 |
monthlyCredit | 300 |
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 6,000 PLN single
given grossMonthly | 6000 |
|---|---|
given under26 | no |
expect zus | 822.6 |
expect health | 465.97 |
expect pit | 291.29 |
expect netMonthly | 4420.14 |
Case 2 — S2 6,000 PLN under 26 — PIT relief
given grossMonthly | 6000 |
|---|---|
given under26 | yes |
expect pit | 0 |
expect netMonthly | 4711.43 |
Sources
- podatki.gov.pl · checked 2026-08-02
- ZUS · 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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