How to Verify VAT Numbers: Formats, VIES Limitations, and Country‑by‑Country Compliance Guide

1 The Problem Isn't Knowledge — It's Reliability

Every finance team knows they should verify VAT numbers. Most try. The issue is that the system they depend on — the EU's VIES portal — is unreliable, limited, and increasingly insufficient for what regulators now expect.

VIES goes down multiple times per month. Not for minutes — for hours. During filing periods and year-end closes, country databases become intermittently unavailable. Over a bad three-day stretch in January 2023, VIES couldn't validate Belgian VAT numbers roughly 32% of the time. Germany was equally bad.

10% of VIES API requests take over one second — and some take over 50 seconds. If you're validating during checkout, onboarding, or invoice processing, that's a workflow-breaking delay.

VIES doesn't contain all valid VAT numbers. Several EU countries only activate numbers for VIES after a separate cross-border registration. A business can be fully VAT-registered domestically in Germany or Spain but invisible to VIES. A "not found" doesn't always mean fraud — it might mean incomplete registration.

2 What Verification Actually Means

Validation checks structure: Is DE123456789 the right format? Does it have 9 digits after the DE prefix? This catches typos.

Verification checks reality: Is this number actively registered with the tax authority right now? Does the entity name match the supplier on your invoice? This catches fraud.

Full verification means confirming three things in sequence:

1. Format correctness — matches the country's structure rules
2. Active registration — live in the tax authority's registry
3. Entity match — registered name and address match your supplier

If your process only does step 1, you're validating — not verifying. Validation alone doesn't protect you from anything that matters.

3 Country-by-Country Traps That Break Your Process

VAT verification isn't one system. It's 27+ separate national databases with different rules, formats, and failure modes.

EU VAT Formats Reference

Non-EU Registries

4 The Real Cost: Worked Examples

5 The 2026–2028 E-Invoicing Cliff

Everything above was about audit risk. What's coming next is operational: invoices will be rejected by systems, not flagged by auditors.

The shift: from "verify to avoid audit risk" to "verify or your invoice doesn't exist." Invalid VAT number = invoice rejected at transmission. No workaround.

6 Why VIES Alone Can't Be Your Strategy

7 Where VAT Verification Fits in Your Stack

Sample API Response

{
  "vatNumber": "DE123456789",
  "valid": true,
  "status": "ACTIVE",
  "countryCode": "DE",
  "companyName": "Mustermann GmbH",
  "companyAddress": "Musterstraße 1, 10115 Berlin",
  "requestDate": "2026-02-22T14:30:00Z",
  "source": "national_registry",
  "sourceNote": "BZSt direct (VIES bypassed)"
}

8 The Operational Playbook

At onboarding: Verify before the vendor master record is created. Compare the registered entity name against the contract. Flag mismatches. Reject inactive numbers. Store results with timestamps.

Before each VAT return: Re-verify every supplier on the upcoming return. The Czech Republic mandates verification on date of supply for input deductions. Estonia and Latvia recommend the same.

Continuously: The UN's 2025 VAT/GST guidance calls for continuous monitoring. MonitorPay's monitoring fires webhook alerts on deregistrations before your next payment run.

During M&A and ERP migrations: Inherit a vendor file? Run bulk validation before migrating it into your systems.

9 What to Require from Any Verification Tool

Direct registry access. If it just wraps VIES, you inherit VIES's problems. It should query BZSt, HMRC, Agenzia delle Entrate directly.

Global coverage. One API, not 30 integrations.

Bulk processing. 5,000+ checks per batch, not one at a time.

Continuous monitoring. Webhook alerts on status changes.

Structured output. JSON with status, entity, source, timestamp.

Audit trail. Every check. Every result. Big 4–ready.

10 The Deadline Is the Mandate

When Belgium, France, and Poland route invoices through government clearance platforms in 2026, an unverified VAT number creates invoice rejection — not audit risk. Your customer doesn't receive the invoice. You don't get paid. No manual workaround.

Build verification into your workflows now, or scramble to integrate while dealing with rejected invoices and confused customers.

Frequently Asked Questions