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Shopify VAT number validation: what Shopify Tax does, and what an app adds

Since May 2025, Shopify Tax checks the VAT numbers of customers, companies and company locations against VIES and HMRC, and a valid number adds the reverse-charge exemption. Since February 2026, Shopify Tax merchants in the EU or UK can show an optional Company VAT number field at checkout, checked for format and validity at the time of the check. If you use Shopify Tax, that is the place to start. An app of your own is for what it does not cover: a dated record with a consultation number, other tax setups, or a rule that blocks checkout on your own terms.

Check before checkout, read the result during it

Most stores cannot call an API from a checkout function. The pattern that works everywhere: check the number when the buyer registers or when the company is created (your app’s backend), store the result on the customer or company in a metafield, and let checkout logic read the metafield. Enterprise stores with a custom app can call the API from the fetch target of a validation function instead.

Node.js: an app endpoint that checks the number and returns what to store
// Called by your B2B registration form or your app's backend, before the first order.
export async function checkBuyerVat(vatNumber) {
  const res = await fetch("https://veriport.io/api/v1/vat/validate?number=" + encodeURIComponent(vatNumber) +
    "&requester=" + encodeURIComponent(process.env.OWN_VAT_NUMBER) + "&record=true", {
    headers: { Authorization: "Bearer " + process.env.VERIPORT_KEY },
  });
  const body = await res.json();
  if (!res.ok) return { ok: false, retry: body.code === "vies_unavailable", code: body.code };
  // Store these on the customer or company (a metafield), so checkout logic can read them without a network call.
  return { ok: true, valid: body.valid, checkedOn: body.requestDate, source: body.source.kind,
           consultationNumber: body.consultationNumber ?? null };
}

What to store in the metafield

FieldWhy
validThe VIES answer for the number on the day asked.
requestDate, source.checkedAtWhen VIES answered (live) or when the cached answer was obtained.
source.kind, source.stalelive or cache; stale: true when the member state was down and a dated earlier answer was served.
consultationNumberThe Commission’s reference for this check, when you sent requester (your own VAT number) on a paid tier.
name, addressWhat the member state publishes; Germany and a few others publish neither.

Questions

I use Shopify Tax: do I need this?
For the exemption itself, Shopify Tax checks the number. You need a check of your own if you want the consultation number and a dated record outside Shopify, or a rule of your own (for example, refusing B2B checkout without a valid number).
Does the check slow checkout down?
Not with the metafield pattern: the call happens before checkout. Shopify notes that its own admin check can take up to 10 seconds.

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Sources