Guides › Validate VAT numbers in your shop or checkout
Validate VAT numbers in your shop or checkout
Updated: 1 November 2026 · Klik&Shop
Selling B2B to EU customers through your web shop? Validate VAT numbers automatically so you can apply the reverse charge without manual work.
When to check
- In the checkout, as soon as a business customer from another EU country enters a VAT number. If valid, show the price without VAT.
- When creating a customer in your CRM or bookkeeping.
- Before invoicing, especially if the previous check failed due to an outage.
- Periodically for regular customers, e.g. every quarter, with a batch check.
Check server-side
Call the API from your server, not from the browser, so your API key stays secret. Example in JavaScript (Node.js):
const res = await fetch("https://api.klik-shop.nl/v1/vat/" + encodeURIComponent(vat), {
headers: { "X-API-Key": process.env.BTW_API_KEY }
});
const data = await res.json();
if (res.status === 200 && data.valid) {
// valid: apply reverse charge, store name/address with data.checked_at
} else if (res.status === 200) {
// invalid: charge VAT or ask the customer to correct the number
} else if (res.status === 503) {
// VIES outage: accept provisionally, re-check later
}More examples (curl, PHP) in the docs.
Make your checkout resilient
- Validate the format first in the form so typos show up immediately (see format per country).
- Don't reject customers during an outage. On
503, accept the order provisionally. See VIES down. - Use a timeout of about 15 seconds so your checkout never hangs.
- Store the result: number, valid/invalid, name, address and time. It helps your bookkeeping and any audit.
Cost
The EU VAT Check API includes 5 free checks per month, then prepaid credit: €5 for 2,000 checks or €15 for 10,000 checks, no subscription. Repeat checks of the same number within 24 hours come from cache and are fast. Get a free API key and try it now. Want to test one number by hand first? Use the free check.
FAQ
Can I use the API key in my front-end?
No. Anyone could read your key and use your credit. Call the API from your server or a serverless function.
What if VIES is unavailable during checkout?
Accept the order provisionally, possibly with VAT, and re-check the number before finalising the invoice.
Check a VAT number now
5 one-time free checks via VIES, or automate with the API (5 free checks a month).