How the Russia ндс (vat) calculator is verified

Inputs

Input	Field	Type
Amount (RUB)	`amount`	number
Direction	`direction`	string
What is being supplied	`category`	string
No VAT charged by you: 0% export or similar operation, or the buyer accounts for the tax	`reverseCharge`	boolean
Business on the simplified tax system (УСН)	`simplifiedRegime`	boolean
Income for the previous year (RUB) — УСН only	`priorYearTurnover`	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)
Rate for the category	`rate`	`category = 'reduced' ? $const.reducedRate : $const.standardRate`
Rate applied	`effectiveRate`	`reverseCharge ? 0 : rate`
Net	`netAmount`	`direction = 'remove' ? $round(amount / (1 + effectiveRate), 2) : $round(amount, 2)`
НДС	`vatAmount`	`$round(netAmount * effectiveRate, 2)`
Gross	`grossAmount`	`$round(netAmount + vatAmount, 2)`
Must charge VAT	`mustRegister`	`$not(simplifiedRegime) or priorYearTurnover > $const.usnExemptionLimit`

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
`standardRate`	0.22
`reducedRate`	0.1
`usnExemptionLimit`	20000000

Test vectors (5)

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 — R1 10,000 RUB net at 22%

given `amount`	10000
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `simplifiedRegime`	no
given `priorYearTurnover`	0
expect `vatAmount`	2200
expect `grossAmount`	12200
expect `netAmount`	10000

Case 2 — R2 12,200 RUB gross back to net

given `amount`	12200
given `direction`	remove
given `category`	standard
given `reverseCharge`	no
given `simplifiedRegime`	no
given `priorYearTurnover`	0
expect `netAmount`	10000
expect `vatAmount`	2200

Case 3 — R3 food at 10%

given `amount`	10000
given `direction`	add
given `category`	reduced
given `reverseCharge`	no
given `simplifiedRegime`	no
given `priorYearTurnover`	0
expect `vatAmount`	1000
expect `grossAmount`	11000

Case 4 — R4 a УСН business with exactly 20 million of 2025 income is exempt

given `amount`	0
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `simplifiedRegime`	yes
given `priorYearTurnover`	20000000
expect `mustRegister`	false

Case 5 — R5 above it, VAT applies

given `amount`	0
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `simplifiedRegime`	yes
given `priorYearTurnover`	20000001
expect `mustRegister`	true

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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