How the Spain ivtm calculator is verified
Inputs
| Input | Field | Type |
|---|---|---|
| Potencia fiscal (CV) | fiscalCV | number |
| Coeficiente municipal | coefBand | string |
| Coeficiente si « Otro » (entre 1,00 y 2,00) | customCoefficient | 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) |
|---|---|---|
| Coeficiente aplicado | coefficient | ($s := coefBand; $s = 'min' ? $const.coefMin : $s = 'medio' ? $const.coefMedio : $s = 'max' ? $const.coefMax : customCoefficient) |
| Cuota base estatal | baseRate | ($c := fiscalCV; $c < 8 ? 12.62 : $c < 12 ? 34.08 : $c < 16 ? 71.94 : $c < 20 ? 89.61 : 112.00) |
| IVTM anual | ivtm | $round(baseRate * coefficient, 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 |
|---|---|
coefMin | 1 |
coefMedio | 1.5 |
coefMax | 2 |
Test vectors (3)
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 9 CV, coefficient 2 (Madrid)
given fiscalCV | 9 |
|---|---|
given coefBand | max |
expect baseRate | 34.08 |
expect ivtm | 68.16 |
Case 2 — C2 16 CV, coefficient 2
given fiscalCV | 16 |
|---|---|
given coefBand | max |
expect baseRate | 89.61 |
expect ivtm | 179.22 |
Case 3 — C3 9 CV en un municipio con el coeficiente mínimo — la mitad del IVTM
given fiscalCV | 9 |
|---|---|
given coefBand | min |
expect coefficient | 1 |
expect ivtm | 34.08 |
Sources
- TRLRHL art. 95 — BOE · 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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