How to Validate VAT Numbers in JavaScript, Python and PHP

1. Normalize and check the format

Customers type VAT numbers with spaces, dots and dashes. Normalize first, then match the country’s pattern (all formats):

const FORMATS = {
  DE: /^DE\d{9}$/,
  FR: /^FR[0-9A-HJ-NP-Z]{2}\d{9}$/,
  NL: /^NL\d{9}B\d{2}$/,
  // … one entry per country
};

function looksValid(input) {
  const vat = input.toUpperCase().replace(/[\s.\-]/g, "");
  const pattern = FORMATS[vat.slice(0, 2)];
  return Boolean(pattern && pattern.test(vat));
}

2. Check digits (Python)

python-stdnum implements the official check-digit algorithms of every EU country:

from stdnum.eu import vat

vat.is_valid("DE 136 695 976")   # True
vat.compact("DE 136 695 976")    # 'DE136695976'

3. Check the registration with an API

JavaScript (Node.js)

const res = await fetch(
  `https://api.vatcheckapi.com/v2/check?vat_number=${encodeURIComponent(vat)}`,
  { headers: { apikey: process.env.VATCHECKAPI_KEY } },
);
const result = await res.json();
if (result.registration_info?.is_registered) {
  // valid: apply the reverse charge, store result.registration_info.checked_at
}

Python

import os, requests

r = requests.get(
    "https://api.vatcheckapi.com/v2/check",
    params={"vat_number": "LU26375245"},
    headers={"apikey": os.environ["VATCHECKAPI_KEY"]},
    timeout=30,
)
info = r.json().get("registration_info", {})
print(info.get("is_registered"), info.get("name"))

PHP

$ch = curl_init('https://api.vatcheckapi.com/v2/check?vat_number=' . urlencode($vat));
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => ['apikey: ' . getenv('VATCHECKAPI_KEY')],
    CURLOPT_TIMEOUT => 30,
]);
$result = json_decode(curl_exec($ch), true);
$registered = $result['registration_info']['is_registered'] ?? false;

Handle errors

422: the number could not be validated (wrong format or unsupported country). Show the format hint to the user.
503: the national service behind VIES is unavailable. Accept the order, mark the number as unchecked and retry later.

Frequently asked questions

Is a regex enough to validate a VAT number?

No. A regex catches wrong formats, and check-digit algorithms catch most typos, but only VIES or HMRC can tell you whether the number is actually registered.

Should I validate VAT numbers in the browser?

Do the format check in the browser for instant feedback, and the registration check on your server, so your API key stays secret.

Validate VAT numbers in your app

vatcheckapi checks the format and checksum of EU and UK VAT numbers and confirms the registration with VIES and HMRC, with company name and address where the country provides them.

150 free validations every month. No credit card required.

{ "country_code": "LU", "vat_number": "26375245", "format_valid": true, "checksum_valid": true, "registration_info": { "is_registered": true, "name": "AMAZON EUROPE CORE S.A R.L.", "address": "38, AVENUE JOHN F. KENNEDY\nL-1855 LUXEMBOURG", "checked_at": "2023-01-11T12:30:28.000000Z" } }

Validate VAT numbers in code