How the Austria umsatzsteuer (vat) calculator is verified

Inputs

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

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 RegistermustRegisterpriorYearTurnover > $const.registrationThreshold or annualTurnover > $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
standardRate0.2
superReducedRate0.049
reducedRate10.1
reducedRate20.13
registrationThreshold55000

Test vectors (7)

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
given priorYearTurnover0
expect vatAmount20
expect grossAmount120
expect netAmount100

Case 2 — S2 120.00 EUR gross back to net at the standard rate

given amount120
given directionremove
given categorystandard
given reverseChargeno
given annualTurnover0
given priorYearTurnover0
expect netAmount100
expect vatAmount20

Case 3 — S3 100.00 EUR net at the 4,9% basic-food rate

given amount100
given directionadd
given categorysuperReduced
given reverseChargeno
given annualTurnover0
given priorYearTurnover0
expect vatAmount4.9
expect grossAmount104.9

Case 4 — S4 100.00 EUR net at the 10% rate

given amount100
given directionadd
given categoryreduced1
given reverseChargeno
given annualTurnover0
given priorYearTurnover0
expect vatAmount10
expect grossAmount110

Case 5 — S5 100.00 EUR net at the 13% rate

given amount100
given directionadd
given categoryreduced2
given reverseChargeno
given annualTurnover0
given priorYearTurnover0
expect vatAmount13
expect grossAmount113

Case 6 — S6 either year over 55.000 EUR ends the exemption

given amount100
given directionadd
given categorystandard
given reverseChargeno
given annualTurnover10000
given priorYearTurnover60000
expect mustRegistertrue

Case 7 — S7 both years under the limit

given amount100
given directionadd
given categorystandard
given reverseChargeno
given annualTurnover50000
given priorYearTurnover40000
expect mustRegisterfalse

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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