# DE VAT Number Checksum Validator

> DE VAT Number Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-29).

Validates the checksum of a German VAT (Umsatzsteuer-Identifikationsnummer) number without performing a live registry lookup.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-vat-de?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/de-vat-number-checksum-validator-c67e3c06
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1N9FM85uo1XgruVhB-fjU

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 de-vat-number-checksum-validator-c67e3c06 -d '<json body>'
```

Example prompt: Can you check if the German VAT number DE123456789 has a valid checksum — just the mathematical check, no registry lookup needed?

## When to prefer this

Choose this endpoint when you need a fast, cheap, purely mathematical checksum check on a German VAT number without triggering a live VIES or German tax authority registry lookup. Ideal for pre-validation in forms, invoicing pipelines, or onboarding flows where you want to catch obvious typos or malformed numbers before (optionally) doing a more expensive live registry check. Prefer the free sandbox endpoint /v1/sandbox/check-vat-de first if available.

## Known failure modes

- Empty or missing VAT number string returns an error
- VAT number exceeds 20000 character limit (unlikely in practice)
- Non-DE VAT numbers may return unexpected results since the check is DE-specific
- Malformed input (non-string types) may cause validation errors
- Payment failure (x402) if USDC balance is insufficient

## How this service works

Call when an agent needs whether a DE VAT checksum is valid. No registry lookup. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/check-vat-de first.

## Output

Returns whether the provided German VAT number passes the checksum algorithm (a purely mathematical validity check), without consulting the official VIES or Bundeszentralamt für Steuern registry. The response indicates valid or invalid status based solely on the number's internal checksum.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "000000003"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/de-vat-number-checksum-validator-c67e3c06/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)