How the Nigeria salary after tax calculator is verified

Inputs

Input	Field	Type
Gross monthly pay, all taxable allowances (₦)	`grossMonthly`	number
of which basic salary (₦ / month)	`basicMonthly`	number
of which housing and transport allowances (₦ / month)	`housingTransportMonthly`	number
Rent you pay for your home (₦ / year)	`annualRent`	number
In the contributory pension scheme (8% of basic, housing and transport)	`pensionMember`	boolean
Public-sector employee, or a private-sector employee who opted in to the NHF (2.5% of basic)	`nhfMember`	boolean
Your contribution under the national health insurance scheme (NHIA) (₦ / month)	`healthInsuranceMonthly`	number
National minimum wage (₦ / month)	`minimumWageMonthly`	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)
Gross pay for the year	`grossAnnual`	`$round($n(grossMonthly) * 12, 2)`
Pension 8% for the year	`pensionAnnual`	`pensionMember ? $round($min([$n(basicMonthly) + $n(housingTransportMonthly), $n(grossMonthly)]) * 12 * $const.pensionEmployeeRate, 2) : 0`
National Housing Fund 2.5%	`nhfAnnual`	`nhfMember ? $round($min([$n(basicMonthly), $n(grossMonthly)]) * 12 * $const.nhfRate, 2) : 0`
National health insurance scheme	`healthInsuranceAnnual`	`$round($n(healthInsuranceMonthly) * 12, 2)`
Rent relief	`rentRelief`	`$round($min([$n(annualRent) * $const.rentReliefRate, $const.rentReliefCap]), 2)`
Exempt: pay at or below the minimum wage	`minimumWageExempt`	`$n(grossMonthly) <= $n(minimumWageMonthly)`
Chargeable income	`chargeableIncome`	`$round($max([0, grossAnnual - pensionAnnual - nhfAnnual - healthInsuranceAnnual - rentRelief]), 2)`
Income tax for the year	`incomeTaxAnnual`	`minimumWageExempt ? 0 : $round($bandedCharge(chargeableIncome, [{"upTo": $const.band1, "rate": $const.rate0}, {"upTo": $const.band2, "rate": $const.rate1}, {"upTo": $const.band3, "rate": $const.rate2}, {"upTo": $const.band4, "rate": $const.rate3}, {"upTo": $const.band5, "rate": $const.rate4}, {"upTo": null, "rate": $const.rate5}]), 2)`
Income tax / month (PAYE)	`incomeTaxMonthly`	`$round(incomeTaxAnnual / 12, 2)`
Net / year	`netAnnual`	`$round($max([0, grossAnnual - incomeTaxAnnual - pensionAnnual - nhfAnnual - healthInsuranceAnnual]), 2)`
Net / month	`netMonthly`	`$round(netAnnual / 12, 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
`band1`	800000
`band2`	3000000
`band3`	12000000
`band4`	25000000
`band5`	50000000
`rate0`	0
`rate1`	0.15
`rate2`	0.18
`rate3`	0.21
`rate4`	0.23
`rate5`	0.25
`rentReliefRate`	0.2
`rentReliefCap`	500000
`pensionEmployeeRate`	0.08
`nhfRate`	0.025

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 — N1 ₦500,000 a month (₦300,000 basic, ₦150,000 housing and transport), ₦1.2m rent, no NHF: tax ₦330,000 + 18% of ₦2,328,000

given `grossMonthly`	500000
given `basicMonthly`	300000
given `housingTransportMonthly`	150000
given `annualRent`	1200000
given `pensionMember`	yes
given `nhfMember`	no
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `pensionAnnual`	432000
expect `chargeableIncome`	5328000
expect `incomeTaxAnnual`	749040
expect `netMonthly`	401580

Case 2 — N1b the same pay: rent relief, monthly PAYE and net for the year

given `grossMonthly`	500000
given `basicMonthly`	300000
given `housingTransportMonthly`	150000
given `annualRent`	1200000
given `pensionMember`	yes
given `nhfMember`	no
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `nhfAnnual`	0
expect `rentRelief`	240000
expect `incomeTaxMonthly`	62420
expect `netAnnual`	4818960

Case 3 — N1c the same pay, opted in to the NHF: 2.5% of ₦3.6m basic = ₦90,000, tax ₦330,000 + 18% of ₦2,238,000

given `grossMonthly`	500000
given `basicMonthly`	300000
given `housingTransportMonthly`	150000
given `annualRent`	1200000
given `pensionMember`	yes
given `nhfMember`	yes
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `nhfAnnual`	90000
expect `chargeableIncome`	5238000
expect `incomeTaxAnnual`	732840
expect `netMonthly`	395430

Case 4 — N2 ₦70,000 a month, no pension or NHF: the minimum wage, so exempt (₦6,000 otherwise)

given `grossMonthly`	70000
given `basicMonthly`	50000
given `housingTransportMonthly`	15000
given `annualRent`	0
given `pensionMember`	no
given `nhfMember`	no
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `minimumWageExempt`	true
expect `chargeableIncome`	840000
expect `incomeTaxAnnual`	0

Case 5 — N3 ₦1 a month above the minimum wage: 15% of the ₦40,012 above ₦800,000

given `grossMonthly`	70001
given `basicMonthly`	50001
given `housingTransportMonthly`	15000
given `annualRent`	0
given `pensionMember`	no
given `nhfMember`	no
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `minimumWageExempt`	false
expect `incomeTaxAnnual`	6001.8

Case 6 — N4 ₦3,000,000 chargeable: the 15% band ends at ₦330,000

given `grossMonthly`	250000
given `basicMonthly`	250000
given `housingTransportMonthly`	0
given `annualRent`	0
given `pensionMember`	no
given `nhfMember`	no
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `chargeableIncome`	3000000
expect `incomeTaxAnnual`	330000

Case 7 — N5 rent of ₦3,000,000: 20% would be ₦600,000, capped at ₦500,000

given `grossMonthly`	500000
given `basicMonthly`	300000
given `housingTransportMonthly`	150000
given `annualRent`	3000000
given `pensionMember`	yes
given `nhfMember`	no
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `rentRelief`	500000
expect `chargeableIncome`	5068000

Case 8 — N6 ₦5,000,000 a month, public sector (NHF): ₦54,780,000 chargeable, ₦10,430,000 + 25% of ₦4,780,000

given `grossMonthly`	5000000
given `basicMonthly`	3000000
given `housingTransportMonthly`	1500000
given `annualRent`	0
given `pensionMember`	yes
given `nhfMember`	yes
given `healthInsuranceMonthly`	0
given `minimumWageMonthly`	70000
expect `pensionAnnual`	4320000
expect `nhfAnnual`	900000
expect `incomeTaxAnnual`	11625000

Case 9 — N7 ₦10,000 a month under the national health insurance scheme is deducted too

given `grossMonthly`	500000
given `basicMonthly`	300000
given `housingTransportMonthly`	150000
given `annualRent`	1200000
given `pensionMember`	yes
given `nhfMember`	no
given `healthInsuranceMonthly`	10000
given `minimumWageMonthly`	70000
expect `chargeableIncome`	5208000
expect `incomeTaxAnnual`	727440

Sources

Nigeria Tax Act 2025 (Act No. 7, in force 1 Jan 2026), s.58 and Fourth Schedule · checked 2026-11-01
Nigeria Tax Act 2025 s.30(2)(a): eligible deductions, rent relief 20% up to ₦500,000 · checked 2026-11-01
Pension Reform Act 2014 (PenCom) s.4(1): employee at least 8% of monthly emoluments · checked 2026-11-01
National Housing Fund Act Cap N45 (FMBN, 2004 text) s.4: 2.5% of basic; s.4 replaced by the Business Facilitation Act 2022 s.45 · 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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