How the Malta vat calculator is verified

Inputs

InputFieldType
Amountamountnumber
Directiondirectionstring
What is being suppliedcategorystring
Turnover this calendar yearannualTurnovernumber
B2B reverse charge appliesreverseChargeboolean

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)
Rateratecategory = 'reduced1' ? $const.reducedRate1 : category = 'reduced2' ? $const.reducedRate2 : category = 'superReduced' ? $const.superReducedRate : $const.standardRate
Effective RateeffectiveRatereverseCharge ? 0 : rate
Net AmountnetAmountdirection = 'remove' ? $round(amount / (1 + effectiveRate), 2) : $round(amount, 2)
Vat AmountvatAmount$round(netAmount * effectiveRate, 2)
Gross AmountgrossAmount$round(netAmount + vatAmount, 2)
Must RegistermustRegisterannualTurnover > $const.registrationThreshold

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
standardRate0.18
superReducedRate0.05
reducedRate10.07
reducedRate20.12
registrationThreshold35000

Test vectors (8)

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 100.00 EUR net at the standard rate

given amount100
given directionadd
given categorystandard
given reverseChargeno
given annualTurnover0
expect vatAmount18
expect grossAmount118
expect netAmount100

Case 2 — S2 118.00 EUR gross back to net at 18%

given amount118
given directionremove
given categorystandard
given reverseChargeno
given annualTurnover0
expect netAmount100
expect vatAmount18

Case 3 — S3 100.00 EUR of licensed accommodation at 7%

given amount100
given directionadd
given categoryreduced1
given reverseChargeno
given annualTurnover0
expect vatAmount7
expect grossAmount107

Case 4 — S4 100.00 EUR of securities custody at 12%

given amount100
given directionadd
given categoryreduced2
given reverseChargeno
given annualTurnover0
expect vatAmount12
expect grossAmount112

Case 5 — S5 100.00 EUR of electricity at 5%

given amount100
given directionadd
given categorysuperReduced
given reverseChargeno
given annualTurnover0
expect vatAmount5
expect grossAmount105

Case 6 — S6 at the Domestic threshold exactly, still a small enterprise

given amount100
given directionadd
given categorystandard
given reverseChargeno
given annualTurnover35000
expect mustRegisterfalse

Case 7 — S7 one euro past it, registration is required

given amount100
given directionadd
given categorystandard
given reverseChargeno
given annualTurnover35001
expect mustRegistertrue

Case 8 — S8 reverse charge: the supplier charges no VAT

given amount100
given directionadd
given categorystandard
given reverseChargeyes
given annualTurnover0
expect vatAmount0
expect grossAmount100

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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