How the Australia take-home pay calculator is verified
Inputs
| Input | Field | Type |
|---|---|---|
| Gross annual salary (AUD) | grossAnnual | 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) |
|---|---|---|
| Income tax | incomeTax | ($t := grossAnnual; $round((($t > 18200 ? (($t < 45000 ? $t : 45000) - 18200) : 0) * 0.15) + (($t > 45000 ? (($t < 135000 ? $t : 135000) - 45000) : 0) * 0.30) + (($t > 135000 ? (($t < 190000 ? $t : 190000) - 135000) : 0) * 0.37) + (($t > 190000 ? ($t - 190000) : 0) * 0.45), 2)) |
| Medicare levy (2%) | medicare | ($t := grossAnnual; $round($t <= $const.medicareThreshold ? 0 : $t < $const.medicareUpper ? ($t - $const.medicareThreshold) * $const.medicareShadeRate : $t * $const.medicareRate, 2)) |
| Net / year | netAnnual | $round(grossAnnual - incomeTax - medicare, 2) |
| Net / month | netMonthly | $round(netAnnual / 12, 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 |
|---|---|
medicareRate | 0.02 |
medicareThreshold | 28011 |
medicareUpper | 35013 |
medicareShadeRate | 0.1 |
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 85,000 AUD
given grossAnnual | 85000 |
|---|---|
expect incomeTax | 16020 |
expect medicare | 1700 |
expect netAnnual | 67280 |
Case 2 — S3 200,000 AUD
given grossAnnual | 200000 |
|---|---|
expect incomeTax | 55870 |
expect medicare | 4000 |
expect netAnnual | 140130 |
Sources
- ATO — individual rates · 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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