# US EIN Format and Prefix Validator

> US EIN Format and Prefix Validator is a paid API for AI agents from bank-validators.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-02).

Validates a US Employer Identification Number (EIN) by checking its format and whether its 2-digit prefix is a valid IRS-assigned prefix — format only, not real-time IRS existence lookup.

## Facts

- Endpoint: GET https://bank-validators.x402tookit.com/ein-format?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-ein-format-and-prefix-validator-8da2dcf9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LAtHSFzUZyFsYx7IXfElv

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 us-ein-format-and-prefix-validator-8da2dcf9
```

Example prompt: Can you check whether the EIN 12-3456789 is properly formatted and has a valid IRS-assigned prefix?

## When to prefer this

Use this endpoint when you need fast, cheap, offline-style validation of a US EIN's format and IRS prefix assignment — ideal for pre-screening form submissions, vendor onboarding, or payroll data quality checks where real-time IRS existence lookup is unnecessary or unavailable. Prefer this over full IRS lookup when speed and cost matter and format correctness is sufficient.

## Known failure modes

- Malformed EIN string (missing dash, wrong digit count) returns invalid verdict with reasons
- Unrecognized or unassigned IRS prefix returns invalid verdict with prefix flagged
- Missing required 'ein' query parameter returns an error
- Non-numeric characters in EIN cause format failure
- Service may return degraded=true if reference data is stale

## How this service works

Check a US EIN's format and whether its 2-digit prefix is one the IRS assigns. Format only, not existence.

## Output

Returns a verdict (valid/invalid), the formatted EIN, the 2-digit prefix, associated IRS issuing campuses, a human-readable summary, reasons for any failure, a disclaimer clarifying this is format-only (not existence), and a list of checks not performed.

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "ein"
     ],
     "properties": {
      "ein": {
       "type": "string",
       "description": "US employer identification number, NN-NNNNNNN, e.g. 12-3456789"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "prefix": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "formatted": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "issuingCampuses": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-ein-format-and-prefix-validator-8da2dcf9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bank-validators.x402tookit.com](https://www.zero.xyz/host/bank-validators.x402tookit.com/llms.txt)