# Toll402 Vietnamese MST (Enterprise/Tax Code) Validator

> Toll402 Vietnamese MST (Enterprise/Tax Code) Validator is a paid API for AI agents from toll402.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Validates a Vietnamese Enterprise or Tax Code (Mã số thuế, MST) using offline structural regex checks for both head-office (10-digit) and branch (13-character) formats.

## Facts

- Endpoint: POST https://toll402.dev/v1/t/mst_vn_validate
- 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/toll402-vietnamese-mst-enterprise-tax-code-validator-164a9838
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NtO0Lv1qfYYTuU5qi1x-v

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 toll402-vietnamese-mst-enterprise-tax-code-validator-164a9838 -d '<json body>'
```

Example prompt: Can you check whether '0101243150-001' is a valid Vietnamese tax code (MST)? I need to know if the format is correct before I use it on an invoice.

## When to prefer this

Choose this endpoint when you need fast, offline, zero-dependency structural validation of Vietnamese MST strings without calling the Vietnamese government's official portal. It is ideal for pre-submission data quality checks, ETL pipelines, and onboarding workflows where network access to official registries is unavailable or undesirable. It does not perform live registry lookups, so pair it with an official database check if full legal confirmation is required.

## Known failure modes

- Input string is empty or missing — returns validation failure
- Input contains non-numeric characters beyond the allowed dash separator — returns invalid
- Ambiguous borderline strings (e.g. 11 digits) that match neither pattern — returns invalid
- The check-digit modulus-11 algorithm is not applied since the official weight table is not consistently published — format-valid codes may still be numerically invalid per official rules

## How this service works

Offline structural validator for a Vietnamese Enterprise/Tax Code (Mã số thuế, MST). Strips spaces, checks the 10-digit head-office pattern or the 13-character branch pattern (10 digits + '-' + 3-digit sequence). Uses regex only since the official modulus-11 check-digit weight table is not consistently published.

## Output

Returns a structured response indicating whether the input string is a valid Vietnamese MST, distinguishing between the 10-digit head-office pattern and the 13-character branch pattern (10 digits + '-' + 3-digit suffix), and whether stripping spaces changes the result.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "value"
     ],
     "properties": {
      "value": {
       "type": "string",
       "description": "MST string, e.g. '0101243150' or '0101243150-001'"
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/toll402-vietnamese-mst-enterprise-tax-code-validator-164a9838/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from toll402.dev](https://www.zero.xyz/host/toll402.dev/llms.txt)