Developer API

Free, no API key, no rate-limited tiers — the same PAYE and VAT math TaxLane's calculators use, as a JSON API.

POST /v1/paye

Calculates PAYE tax exactly the way the PAYE calculator does. Only grossAnnualIncome is required — every other field defaults to 0.

curl -X POST https://w6kbad7pff.execute-api.us-east-1.amazonaws.com/v1/paye \
  -H "content-type: application/json" \
  -d '{"grossAnnualIncome": 6000000, "annualRentPaid": 1200000}'

Request fields

FieldTypeRequiredDefault
grossAnnualIncomenumberYes
secondaryAnnualIncomenumberNo0
annualRentPaidnumberNo0
terminationBenefitnumberNo0
pensionContributionnumberNo0
nhfContributionnumberNo0
nhisContributionnumberNo0
lifeAssurancePremiumContributionnumberNo0

Response

The full PAYE result: taxableIncome, payeTax, annualTax, monthlyTax, a reliefs breakdown, and a bandBreakdown array showing how much tax fell in each band.

{
  "taxableIncome": 6000000,
  "payeTax": 870000,
  "annualTax": 870000,
  "monthlyTax": 72500,
  "reliefs": {
    "rentRelief": 0,
    "pensionRelief": 0,
    "nhfRelief": 0,
    "nhisRelief": 0,
    "lifeAssurancePremiumRelief": 0,
    "minimumWageExempt": false,
    "taxableTerminationBenefit": 0
  },
  "bandBreakdown": [
    { "from": 800000, "to": 3000000, "rate": 0.15, "taxInBand": 330000 },
    { "from": 3000000, "to": 6000000, "rate": 0.18, "taxInBand": 540000 }
  ]
}

POST /v1/vat

Calculates VAT exactly the way the VAT calculator does, at the standard 7.5% rate.

curl -X POST https://w6kbad7pff.execute-api.us-east-1.amazonaws.com/v1/vat \
  -H "content-type: application/json" \
  -d '{"amount": 100000, "mode": "exclusive"}'

Request fields

FieldTypeRequiredDefault
amountnumberYes
mode"exclusive" | "inclusive"Yes
zeroRatedbooleanNofalse

Response

net, vat, and gross amounts.

{
  "net": 100000,
  "vat": 7500,
  "gross": 107500
}

Errors

A missing or non-numeric required field returns 400 with an error message. An unknown route returns 404. Negative numbers are not rejected — they're clamped internally, matching the calculator UI's own behavior for the same input.

Limits

No API key required, no daily cap. Requests are limited to 50 per second (100 burst) at the shared Gateway level to keep the service available for everyone.

For guidance only — not tax advice.