Tax ID Validator

Overview

Tax ID Validator removes spaces and hyphens from `taxid` and requires exactly nine digits; anything else returns `valid: false`, `type` Unknown, a format error and a fixed `risk_score` of 50. The type is then inferred from shape alone. A number starting with 9 is treated as an ITIN. A number written with a hyphen after the second digit (XX-XXXXXXX) is treated as an EIN. Every other nine-digit number is treated as an SSN. Because the leading 9 check runs first, an EIN with a 9x prefix is classified and validated as an ITIN, so send hyphen-formatted EINs and read `type` before trusting the result.

SSN rules reject area 000, 666 and 900 to 999, group 00 and serial 0000, stopping at the first failure, which is reported in `error` and the matching `validation_details` flag. EINs must start with one of the two-digit prefixes the IRS has assigned; unassigned prefixes such as 07, 08, 09, 17 or 89 fail `prefix_valid`. ITINs must have middle digits in 50 to 65, 70 to 88, 90 to 92 or 94 to 99, checked by `itin_range_valid`.

`normalized` is the hyphenated standard form, `digits_only` the bare digits, `last4` the final four, and `masked` hides all but those four (***-**-6789, or **-****6789 for an EIN). `taxid` echoes the input as sent. `is_placeholder` is true for all-identical digits or a strict ascending or descending run such as 123456789. `risk_score` adds 40 for a failed rule and 35 for a placeholder, so a valid placeholder scores 35; `risk_level` is high at 60 or above, medium at 25 or above, otherwise low. On the Free plan `type`, `type_full`, `format`, `is_placeholder`, the risk fields and the SSN component flags are null.

Live Test Tax ID Validator API →

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

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curl "https://api.apiverve.com/v1/taxidvalidator?taxid=123-45-6789" \
  -H "x-api-key: your_api_key_here"

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const res = await fetch('https://api.apiverve.com/v1/taxidvalidator?taxid=123-45-6789', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);

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import requests

res = requests.get(
    "https://api.apiverve.com/v1/taxidvalidator?taxid=123-45-6789",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])

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package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/taxidvalidator?taxid=123-45-6789", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

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{
  "status": "ok",
  "error": null,
  "data": {
    "valid": true,
    "taxid": "123-45-6789",
    "type": "SSN",
    "type_full": "Social Security Number",
    "format": "XXX-XX-XXXX",
    "normalized": "123-45-6789",
    "digits_only": "123456789",
    "masked": "***-**-6789",
    "last4": "6789",
    "is_placeholder": true,
    "validation_details": {
      "format_valid": true,
      "area_number_valid": true,
      "group_number_valid": true,
      "serial_number_valid": true
    },
    "risk_score": 35,
    "risk_level": "medium",
    "error": null
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

Use cases

Form Validation

Validate Tax IDs in online forms and applications to ensure correct format before submission

Compliance

Verify Tax ID format compliance for tax reporting, payroll processing, and financial services

Data Quality

Validate Tax IDs in databases during data cleaning and migration to identify invalid entries

Identity Verification

Check Tax ID format as part of identity verification processes while maintaining privacy with masking

Other ways to use Tax ID Validator

Set up Tax ID Validator on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

Related

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