# Agent402 VAT Number Format Validator

> Agent402 VAT Number Format Validator is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Validates VAT number format against official rules for EU27, GB, XI, and EL country codes without performing live VIES database checks

## Facts

- Endpoint: POST https://agent402.co.uk/v1/validate/vat-format
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-vat-number-format-validator-7f7c8bbc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IknADV9DiO0S0B3_4yV1I

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agent402-vat-number-format-validator-7f7c8bbc -d '<json body>'
```

Example prompt: Before I issue this invoice, can you check whether DE123456789 is a validly formatted German VAT number — just the structure, not a live VIES lookup?

## When to prefer this

Use this endpoint as a lightweight pre-flight check before any tax, invoice, or B2B payment workflow where you need to confirm a VAT number is structurally plausible without triggering a live VIES call. Prefer it when you want fast, cheap, offline structural validation across EU27, GB, XI, and EL country codes. It is not a substitute for live VIES validation when legal compliance requires confirmed registration status.

## Known failure modes

- Unrecognized country prefix returns known_rule: false with valid_format: false
- Malformed input with no prefix and no country parameter may return an error or ambiguous result
- Country code mismatch between prefix and optional country parameter may produce inconsistent results
- EL vs GR ambiguity for Greece may cause issues if not handled correctly by caller
- No live registry check means a structurally valid number may still be unregistered

## 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 containing the resolved country code (e.g. 'DE'), a boolean 'valid_format' indicating whether the VAT number matches the country's structural rules, and a boolean 'known_rule' indicating whether Agent402 has a format rule for that country. Does not perform live VIES registry lookups.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "vat": {
   "type": "string",
   "description": "VAT with country prefix"
  },
  "country": {
   "type": "string",
   "description": "Optional ISO if body has no prefix"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "country": "DE",
  "known_rule": true,
  "valid_format": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-vat-number-format-validator-7f7c8bbc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.co.uk](https://www.zero.xyz/host/agent402.co.uk/llms.txt)