How the Nigeria VAT calculator is verified

Inputs

Input	Field	Type
Amount (₦)	`amount`	number
This amount is	`direction`	string
What is being supplied	`category`	string
Your business bought from a non-resident that did not charge VAT (s.150(2))	`reverseCharge`	boolean
Your annual turnover (₦)	`annualTurnover`	number
Your total fixed assets (₦)	`fixedAssets`	number
The business provides professional services	`professionalServices`	boolean

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	`rate`	`category = 'standard' ? $const.vatRate : $const.zeroRate`
Effective Rate	`effectiveRate`	`reverseCharge ? 0 : rate`
Value excluding VAT	`netAmount`	`direction = 'remove' ? $round(amount / (1 + effectiveRate), 2) : $round(amount, 2)`
VAT charged	`vatAmount`	`$round(netAmount * effectiveRate, 2)`
VAT you self-account and remit (s.150(2))	`selfAccountedVat`	`reverseCharge ? $round(netAmount * rate, 2) : 0`
Gross	`grossAmount`	`$round(netAmount + vatAmount, 2)`
Must register, charge VAT and file monthly	`mustRegister`	`$n(annualTurnover) > $const.smallBusinessTurnover or $n(fixedAssets) > $const.smallBusinessFixedAssets or professionalServices`

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
`vatRate`	0.075
`zeroRate`	0
`smallBusinessTurnover`	100000000
`smallBusinessFixedAssets`	250000000

Test vectors (9)

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 — V1 ₦100,000 of taxable goods: 7.5% = ₦7,500

given `amount`	100000
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `annualTurnover`	0
given `fixedAssets`	0
given `professionalServices`	no
expect `vatAmount`	7500
expect `grossAmount`	107500
expect `effectiveRate`	0.075

Case 2 — V2 ₦107,500 including VAT back to ₦100,000

given `amount`	107500
given `direction`	remove
given `category`	standard
given `reverseCharge`	no
given `annualTurnover`	0
given `fixedAssets`	0
given `professionalServices`	no
expect `netAmount`	100000
expect `vatAmount`	7500

Case 3 — V3 zero-rated basic food: 0%

given `amount`	100000
given `direction`	add
given `category`	zeroRated
given `reverseCharge`	no
given `annualTurnover`	0
given `fixedAssets`	0
given `professionalServices`	no
expect `rate`	0
expect `vatAmount`	0
expect `grossAmount`	100000

Case 4 — V4 an exempt supply of land carries no VAT

given `amount`	100000
given `direction`	add
given `category`	exempt
given `reverseCharge`	no
given `annualTurnover`	0
given `fixedAssets`	0
given `professionalServices`	no
expect `vatAmount`	0
expect `grossAmount`	100000

Case 5 — V5 ₦200,000 of services from a non-resident: the buyer self-accounts ₦15,000

given `amount`	200000
given `direction`	add
given `category`	standard
given `reverseCharge`	yes
given `annualTurnover`	0
given `fixedAssets`	0
given `professionalServices`	no
expect `vatAmount`	0
expect `selfAccountedVat`	15000
expect `grossAmount`	200000

Case 6 — V6 turnover of exactly ₦100 million is still a small business

given `amount`	100000
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `annualTurnover`	100000000
given `fixedAssets`	0
given `professionalServices`	no
expect `mustRegister`	false

Case 7 — V7 ₦1 above ₦100 million must register

given `amount`	100000
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `annualTurnover`	100000001
given `fixedAssets`	0
given `professionalServices`	no
expect `mustRegister`	true

Case 8 — V8 professional services are never a small business

given `amount`	100000
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `annualTurnover`	5000000
given `fixedAssets`	0
given `professionalServices`	yes
expect `mustRegister`	true

Case 9 — V9 fixed assets above ₦250 million must register

given `amount`	100000
given `direction`	add
given `category`	standard
given `reverseCharge`	no
given `annualTurnover`	5000000
given `fixedAssets`	250000001
given `professionalServices`	no
expect `mustRegister`	true

Sources

Nigeria Tax Act 2025 (Act No. 7, in force 1 Jan 2026) ss.147, 185, 186: 7.5%, exempt, 0% · checked 2026-11-01
Nigeria Tax Administration Act 2025 ss.22(4)-(5), 147: small business ₦100m / ₦250m · checked 2026-11-01

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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