# EIN Format Check

> EIN Format Check is a paid API for AI agents from hcrb.in, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-12).

Validates the format of a US Employer Identification Number (EIN) using offline deterministic rules, returning validity, reason, and normalized form.

## Facts

- Endpoint: POST https://hcrb.in/v1/tools/ein-format-check/call?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ein-format-check-75f08406
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_M7h07aGdZc-vboDyiVIfT

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 ein-format-check-75f08406 -d '<json body>'
```

Example prompt: Can you check whether 12-3456789 is a properly formatted US Employer Identification Number?

## When to prefer this

Choose this endpoint when you need a fast, offline, deterministic EIN format check with no external lookups or ML — ideal for agent pipelines doing KYB onboarding, tax form validation, or data cleanup where low latency and auditability (signed receipts) matter. It is not a registry lookup and will not confirm the EIN belongs to a real business.

## Known failure modes

- Malformed or missing input returns valid:false with a descriptive reason
- Non-EIN identifier submitted returns an error or invalid result
- Payment failure via x402 results in HTTP 402 before processing
- Rate limit exceeded beyond 3 free daily calls without payment

## How this service works

Offline deterministic checks (no ML, no scraping) for business identifiers and rental due-diligence, paid per call via x402 (gasless EIP-3009 USDC on Base). Checksum-verifiable (IBAN, LEI, VAT, ABA, ISBN, SEDOL…) vs format-only (EIN, IFSC, SWIFT/BIC…) — every response returns a scope field. Non-custodial, signed receipts. First 3 calls/day free.

## Output

A JSON object with a boolean 'valid' field, a human-readable 'reason' explaining the result, a 'scope' field indicating whether the check is format-only or checksum-verifiable, a 'normalized' string with the standardized EIN format, and a 'country' field. EIN is a format-only check (no checksum), so 'scope' will reflect that.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "ein"
   ],
   "properties": {
    "ein": {
     "type": "string",
     "description": "US EIN, 9 digits; dashes/spaces allowed."
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "schema": {
  "type": "object",
  "required": [
   "valid",
   "reason"
  ],
  "properties": {
   "tool": {
    "type": "string"
   },
   "scope": {
    "type": "string"
   },
   "valid": {
    "type": "boolean"
   },
   "reason": {
    "type": "string"
   },
   "country": {
    "type": "string"
   },
   "normalized": {
    "type": "string"
   }
  }
 },
 "example": {
  "valid": true,
  "reason": "checksum valid"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ein-format-check-75f08406/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from hcrb.in](https://www.zero.xyz/host/hcrb.in/llms.txt)