How the Poland ryczałt it calculator is verified

Inputs

InputFieldType
Annual revenue (PLN)annualRevenuenumber

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 valueFieldFormula (JSONata)
Ryczałt tax (12%)ryczaltTax$round(annualRevenue * $const.ryczaltRate, 2)
Net income / year (before ZUS)netIncome$round($max([0, annualRevenue - ryczaltTax]), 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.

ConstantValue
ryczaltRate0.12

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 — 200,000 PLN revenue, a typical IT contractor

given annualRevenue200000
expect ryczaltTax24000
expect netIncome176000

Case 2 — 50,000 PLN revenue

given annualRevenue50000
expect ryczaltTax6000
expect netIncome44000

Sources

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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