How the Poland akcyza calculator is verified
Inputs
| Input | Field | Type |
|---|---|---|
| Wartość pojazdu (PLN) | value | number |
| Pojemność silnika (cm³) | displacement | number |
| Hybryda | hybrid | 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) |
|---|---|---|
| Rate | rate | ($r := displacement <= $const.ccThreshold ? $const.lowRate : $const.highRate; hybrid ? $r / 2 : $r) |
| Akcyza | akcyza | $round(value * rate, 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 |
|---|---|
lowRate | 0.031 |
highRate | 0.186 |
ccThreshold | 2000 |
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 — C1 petrol 1,598 cm3 valued 30,000 PLN
given value | 30000 |
|---|---|
given displacement | 1598 |
given hybrid | no |
expect rate | 0.031 |
expect akcyza | 930 |
Case 2 — C2 3.0 L valued 80,000 PLN — high band
given value | 80000 |
|---|---|
given displacement | 3000 |
given hybrid | no |
expect rate | 0.186 |
expect akcyza | 14880 |
Sources
- Akcyza — samochody (podatki.gov.pl) · 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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