EIN structure validate API

Validates US EIN structure (NN-NNNNNNN), rejecting prefixes the IRS never assigns and mapping the prefix to its issuing campus. Answers 'Is this EIN well-formed?', 'Which IRS campus issued this prefix?'.

Price$0.02per request

MethodPOST

Route/v1/validate/ein

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

eintax-idirsvalidatestructureusbusinessfeinprefix

API URLhttps://x402.hexl.dev/v1/validate/ein

Integration docs

Example request

{
  "ein": "12-3456789"
}

Example response

{
  "valid": true,
  "reason": "Valid EIN structure; prefix 12 (Andover). Structure only — not an existence check.",
  "normalized": "12-3456789",
  "prefix": "12",
  "issuingCampus": "Andover"
}

Input schema

{
  "type": "object",
  "required": [
    "ein"
  ],
  "properties": {
    "ein": {
      "type": "string",
      "description": "9-digit Employer Identification Number (hyphen optional).",
      "examples": [
        "12-3456789"
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}