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EU VAT Validation for E-commerce

E-commerce stores selling B2B across EU borders must verify customer VAT numbers before applying zero-rate treatment. Use the TaxID API at checkout to validate EU VAT numbers in real time and prevent costly misapplied tax exemptions.

Implementation steps

1. 1

   Get a free TaxID API key

   Sign up at taxid.dev/signup and store your API key as a server-side environment variable. Never expose it in client-side JavaScript or checkout scripts.

2. 2

   Add a VAT number field to your checkout

   Add a clearly labeled VAT number input to your B2B checkout form. For WooCommerce, use a checkout hook. For Shopify, use a custom storefront field or checkout extension. For custom stores, add the field to your billing section.

3. 3

   Validate via the TaxID API before confirming the order

   On form submission, call GET /api/v1/validate/:country/:vat from your server. Parse the two-character country prefix from the VAT number (e.g., 'DE' from 'DE123456789'). Check that status === 'active' before applying zero-rate. Return a form error for 'invalid'; charge standard VAT for 'service_unavailable'.

4. 4

   Store the validated company details on the order

   Persist the company_name and company_address from the TaxID response alongside the VAT number and validation timestamp in your order database. This audit record is required under EU invoice rules if you are audited.

Code example

const res = await fetch(
  'http://localhost:3000/api/v1/validate/DE/DE123456789',
  { headers: { 'Authorization': 'Bearer YOUR_API_KEY' } }
);
const { valid, status, company_name, company_address } = await res.json();

if (valid) {
  console.log(`Valid EU business: ${company_name}`);
} else if (status === 'service_unavailable') {
  // VIES is temporarily down — retry or allow with manual check
  console.log('VIES unavailable — check back in a few minutes');
} else {
  console.log('Invalid VAT number — charge local tax rate');
}

import requests

res = requests.get(
    "http://localhost:3000/api/v1/validate/DE/DE123456789",
    headers={"Authorization": "Bearer YOUR_API_KEY"}
)
data = res.json()

if data["valid"]:
    print(f"Valid: {data['company_name']}")
elif data["status"] == "service_unavailable":
    print("VIES temporarily unavailable")
else:
    print("Invalid VAT number")

API response

The TaxID API returns a consistent JSON response for every validation request:

{
  "valid": true,
  "status": "active",
  "country_code": "DE",
  "vat_number": "123456789",
  "company_name": "Example GmbH",
  "company_address": "Musterstraße 1, 10115 Berlin",
  "request_date": "2026-05-10T00:00:00.000Z",
  "cached": false,
  "request_id": "req_01j..."
}

Error handling

The API uses a consistent Stripe-style error format. Always handle service_unavailable separately — VIES has occasional downtime and you should not reject valid customers during outages.

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