How the South Africa licence disc calculator is verified
Inputs
| Input | Field | Type |
|---|---|---|
| Tare weight (kg) | tareWeight | 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) |
|---|---|---|
| Annual licence fee | fee | ($w := tareWeight; $round($w <= 1000 ? 300 : $w <= 1500 ? 456 : $w <= 2000 ? 660 : $w <= 2500 ? 900 : 1200, 2)) |
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 Gauteng 1,250 kg
given tareWeight | 1250 |
|---|---|
expect fee | 456 |
Case 2 — C2 Gauteng 2,100 kg
given tareWeight | 2100 |
|---|---|
expect fee | 900 |
Sources
- NaTIS · 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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