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United Kingdom VAT Registration Number Validation API
Validate United Kingdom VAT Registration Number numbers via REST API. Backed by HMRC (real-time) — returns registration status, company name, and address in a single call.
Quick start
CURL
curl -H "Authorization: Bearer YOUR_API_KEY" \ http://localhost:3000/api/v1/validate/GB/GB123456789
Single validation
Validate one United Kingdom VAT Registration Number number. Returns full company details for valid numbers.
const res = await fetch(
'http://localhost:3000/api/v1/validate/GB/GB123456789',
{ headers: { 'Authorization': 'Bearer YOUR_API_KEY' } }
);
const data = await res.json();
/*
{
"valid": true,
"status": "active",
"company_name": "Example GmbH",
"address": "Musterstraße 1, United Kingdom",
"country_code": "GB",
"vat_number": "GB123456789",
"cached": false,
"request_id": "req_01abc..."
}
*/Response format
{
"valid": true,
"status": "active",
"company_name": "Example United Kingdom Ltd",
"address": "Musterstraße 1, United Kingdom",
"country_code": "GB",
"vat_number": "GB123456789",
"cached": false,
"request_id": "req_01abc..."
}| Field | Type | Description |
|---|---|---|
| valid | boolean | true if the number is registered and active |
| status | string | "active", "inactive", "not_found", or "invalid_format" |
| company_name | string | null | Registered company name (where available from authority) |
| address | string | null | Registered address (where available from authority) |
| country_code | string | ISO 2-letter code — always "GB" for this endpoint |
| vat_number | string | The VAT number as sent in the request |
| cached | boolean | true if result served from cache (valid: 24h, invalid: 1h) |
| request_id | string | Unique request ID for support and audit logs |
Batch validation
Validate up to 25 numbers in a single POST request. Numbers are processed in parallel — ideal for onboarding flows and nightly reconciliation.
curl -s -X POST http://localhost:3000/api/v1/validate \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"numbers": [
{ "country": "GB", "vat": "GB123456789" },
{ "country": "GB", "vat": "GB123456789" }
]
}'[
{
"vat": "GB123456789",
"valid": true,
"status": "active",
"company_name": "Example Ltd",
"country_code": "GB",
"cached": false
},
{
"vat": "GB123456789",
"valid": false,
"status": "not_found",
"country_code": "GB",
"cached": false
}
]Error codes
| HTTP status | Meaning | Action |
|---|---|---|
| 400 | Bad request — malformed VAT format | Check the VAT format against the pattern below |
| 401 | Missing or invalid API key | Pass a valid Bearer token in the Authorization header |
| 404 | Country not supported | Check /vat-api for the full list of supported countries |
| 422 | Validation failed — invalid format | The number does not match the expected format |
| 429 | Rate limit exceeded | Back off and retry after the Retry-After header value |
| 503 | Upstream authority unavailable | VIES/authority is temporarily down — retry with exponential backoff |
United Kingdom VAT Registration Number format reference
| Property | Value |
|---|---|
| Country code (ISO) | GB |
| Local name | VAT Registration Number |
| Format | GB + 9 digits |
| Regex | ^GB[0-9]{9}$ |
| Example | GB123456789 |
| Standard rate | 20% |
| Validation source | HMRC (real-time) |
| VIES supported | No |
Since Brexit (January 2021), the UK is no longer part of the EU VAT system and cannot be validated via VIES. UK VAT numbers are validated directly through the HMRC API. UK businesses selling digitally to EU customers must register for VAT in an EU member state or use the OSS scheme.
Frequently asked questions
What does the TaxID API return for a United Kingdom VAT Registration Number validation?
For a valid United Kingdom VAT Registration Number number the API returns: `valid: true`, `status: "active"`, plus `company_name` and `address` where available from HMRC (real-time). For invalid numbers it returns `valid: false` with a reason code. All fields are documented in the API reference.
How fast is the United Kingdom VAT Registration Number validation API?
Cached results (valid numbers are cached 24h, invalid 1h) respond in under 10ms. Uncached requests that require a live lookup via HMRC (real-time) typically complete in 100–400ms. The `cached` field in the response tells you whether the result came from cache.
What is the United Kingdom VAT Registration Number number format?
United Kingdom VAT Registration Number numbers (VAT Registration Number) follow the pattern: GB + 9 digits. A valid example is `GB123456789`. The TaxID API validates the format locally before making any live request, so malformed numbers fail instantly without consuming your quota.
Can I validate multiple United Kingdom VAT Registration Number numbers in one request?
Yes. The batch endpoint (POST /api/v1/validate) accepts up to 25 VAT numbers in a single request, processed in parallel. This is ideal for bulk onboarding flows, nightly reconciliation jobs, or importing customer lists. Each item in the response array maps 1-to-1 with your input array.
Start validating United Kingdom VAT Registration Number numbers
Free plan — 100 validations/month. No credit card required.
Integrate with your stack:
More United Kingdom resources:
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