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Agent402 UK VAT Number Format Validator
x402
Agent402 UK VAT Number Format Validator is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).
Validates UK VAT number format (GB/XI prefix + digits, or GD/HA) using pure logic — no live HMRC or VIES lookup required.
Price / call$0.001
Success—
StatusDown
How this service works
Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.
Output
Returns a JSON object with the parsed VAT prefix (e.g. 'GB', 'XI', 'GD', 'HA'), the normalized electronic format string, and a boolean 'valid_format' field indicating whether the number conforms to UK VAT formatting rules. Does not confirm HMRC registration status.
Example use cases
Invoice processing pre-flight check
“We're about to process a UK supplier invoice — can you validate that 'GB987654321' is a properly formatted UK VAT number before we submit it to our accounting system?”
Onboarding UK business verification
“A new vendor just signed up and gave us the VAT number 'XI123456789012' — can you check whether that's a valid UK VAT format before we approve their account?”
E-commerce checkout VAT gate
“A customer entered 'GD498' as their VAT number at checkout — is that a valid UK VAT number format? I need to know before we apply VAT exemption.”
Technical details
Endpoint
POSThttps://agent402.co.uk/v1/validate/uk-vatWhen to prefer
Use this endpoint when you need a fast, cheap, offline-style format check on a UK VAT number before invoking live HMRC or VIES verification. Ideal as a pre-action gate in tax workflows, invoice processing pipelines, or business onboarding flows where you want to catch obviously malformed VAT numbers without incurring network latency or rate limits from government APIs.
Side effects
- Invalid or missing 'vat' field returns valid_format: false
- Unrecognized prefix (not GB, XI, GD, HA) returns valid_format: false
- Wrong digit count for GB/XI (must be 9 or 12 digits) returns valid_format: false
- Empty string input may return an error or valid_format: false
- Non-string input may cause a 400 or schema error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| vat | string | VAT number |
Output
Schema · Response
{
"type": "json",
"example": {
"prefix": "GB",
"electronic": "GB123456789",
"valid_format": true
}
}Tags
x402
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