# Bulgarian VAT Number Checksum Validator

> Bulgarian VAT Number Checksum Validator is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-02).

Validates whether a Bulgarian VAT number passes the official checksum algorithm, without performing any live registry lookup.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-vat-bg?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bulgarian-vat-number-checksum-validator-7b9bf13b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1uOj27albcUL7mspd25Ns

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 bulgarian-vat-number-checksum-validator-7b9bf13b -d '<json body>'
```

Example prompt: Can you check if the Bulgarian VAT number BG123456789 passes the checksum — I just need to know if it's structurally valid, no registry lookup needed.

## When to prefer this

Use this endpoint when you need a fast, cheap, offline checksum validation of a Bulgarian VAT number and do not need to confirm the number is actually registered with the Bulgarian tax authority. Ideal for pre-submission validation, data cleaning, or form input verification where a registry lookup is unnecessary or too slow. Prefer the free sandbox endpoint /v1/sandbox/check-vat-bg for testing.

## Known failure modes

- Input value is empty or missing — returns validation error
- Input exceeds 20000 characters — rejected by schema
- Malformed request body — returns 400 or similar client error
- Payment not attached or insufficient USDC — returns 402 Payment Required
- Non-string or non-BG VAT format passed — may return false validity or error

## How this service works

Call when an agent needs whether a BG VAT checksum is valid. No registry lookup. Exact $0.003 USDC. Prefer unpaid POST /v1/sandbox/check-vat-bg first.

## Output

A boolean or structured response indicating whether the provided Bulgarian VAT number passes the official BG VAT checksum algorithm. No live registry or government database is queried — only the algorithmic checksum is evaluated.

## 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": [
    "000000018"
   ],
   "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/bulgarian-vat-number-checksum-validator-7b9bf13b/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)