What Is a VAT ID? A Plain Guide

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What Is a VAT ID (VAT Identification Number)?

A VAT ID is the number a tax authority gives a business when it registers for value-added tax, and it identifies that business for VAT everywhere it trades. In the EU it is written as a two-letter country prefix followed by a country-specific string — DE123456789, for example — and it shows up on invoices and in cross-border B2B transactions.

This guide covers what a VAT ID actually is, what it is used for, how it is structured, and how to confirm one is real. The scope here is the EU-27 plus XI (Northern Ireland), which is the area VIES covers.

If you just want to confirm a number right now, you can jump to checking whether a VAT ID is valid. Otherwise, start from the top.

What a VAT ID actually is

A VAT ID (VAT identification number) is issued by a national tax authority when a business registers for VAT. From that point on, the number is how the business is recognised in the VAT system: it goes on the invoices it issues, it is quoted when trading with other VAT-registered businesses, and it is the value other parties look up to confirm the business is registered.

A VAT ID is tied to VAT specifically. It is not a general-purpose company identifier, and it is not the number your bank or a supplier's accounts-payable team would use for anything else.

VAT ID vs VAT registration number vs local tax number

These three phrases cause most of the confusion, so to be direct: "VAT ID", "VAT number", and "VAT registration number" are the same thing. Different documents and different countries use different wording, but they all refer to the one identifier a business uses for VAT.

What a VAT ID is not is a domestic tax number or a company registration number:

• A local tax number is what the domestic tax office uses to administer a business internally. In several countries it looks different from the VAT ID and is used for filings that have nothing to do with cross-border trade. It usually has no country prefix, so it will not validate as an EU VAT ID.
• A company registration number is issued by a company register (the equivalent of Companies House, the Handelsregister, and so on) when the entity is incorporated. It identifies the legal entity, not its VAT status.

A business can have all three, and they are typically different values. On an intra-EU invoice, the one that belongs there is the VAT ID with its country prefix.

What a VAT ID is used for

Intra-EU B2B trade

The VAT ID's main job is cross-border business-to-business trade inside the EU. When two VAT-registered businesses in different member states trade, they exchange VAT IDs so each side can establish that the other is a registered taxable person. That single fact changes how VAT is handled on the transaction.

Invoicing

A VAT ID belongs on VAT invoices. For intra-EU B2B supplies, both the supplier's and the customer's VAT IDs generally appear on the invoice — and the customer's number being present and valid is part of what supports the correct VAT treatment of the supply.

Reverse charge

When a valid buyer VAT ID is present on a cross-border B2B supply, the seller can often avoid charging local VAT — but the exact mechanism depends on what is sold. For goods, the sale can be an exempt (zero-rated) intra-Community supply, with the buyer accounting for VAT on the acquisition in their own country. For services, the place of supply generally shifts to the buyer, who accounts for the VAT under the reverse-charge mechanism. Either way, a valid buyer VAT ID is one of the conditions that has to hold — the full set of conditions is its own topic; see how reverse charge works for cross-border B2B. The point for this guide is that the buyer's VAT ID is central to that treatment, which is exactly why sellers care whether it is valid.

How a VAT ID is structured

At a glance, an EU VAT ID is:

[2-letter country prefix] + [up to ~12 alphanumeric characters]

For example, a German VAT ID looks like DE123456789: the DE prefix, then the national portion. The national portion varies by country — some are all digits, some include letters, and lengths differ — so the "up to ~12 characters" is a rough envelope, not a single fixed pattern.

Two prefixes catch people out:

• Greece uses EL, not GR. The VAT system uses EL even though the ISO country code is GR.
• Northern Ireland uses XI. Under the Northern Ireland arrangements (Windsor Framework), NI VAT IDs for goods carry the XI prefix and are validatable through VIES.

Per-country patterns are worth a reference when you need them, but there is no reason to memorise 27 of them. The full breakdown is here: VAT number formats for all 27 EU countries.

VAT ID vs other identifiers people confuse it with

A VAT ID gets mixed up with several other business numbers. Quick disambiguation, staying strictly on VAT:

• It is not an EORI number. An EORI number identifies businesses for customs, not VAT.
• It is not an IOSS or OSS registration. Those are separate VAT special-scheme registrations (IOSS even issues its own IM-prefixed number), distinct from the VAT ID itself.
• It is not a company registration number. That comes from the company register and identifies the legal entity, not its VAT status.

If a number has a two-letter country prefix and validates in VIES, it is a VAT ID. The others do not behave that way.

How to check whether a VAT ID is valid

For EU VAT IDs, validity is confirmed against VIES, the European Commission's system that routes a query to the relevant national VAT database and reports back whether the number is registered; some numbers can also be cross-checked against national registries.

A valid format is not the same as a valid number. A string can match a country's pattern
perfectly and still not be a registered, active VAT ID — the difference between the two, and the
third state most people miss, is spelled out in VAT ID format vs
valid. Only a live check against VIES or a national source tells
you whether the number actually exists and is active — never infer registration from the shape of
the string alone.

For a single number, the fastest route is a free VAT number checker — paste the VAT ID in and you get the live result. If you want to understand what sits behind that result, including why VIES sometimes can't answer, read what VIES is and how it works.

When a business needs to validate other companies' VAT IDs

Checking one number by hand is fine. Checking VAT IDs on every signup, every invoice, or across an existing customer base is not — that is where you validate programmatically.

At that point you call a validation service from your own application: a VIES API for EU-wide lookups, or a per-country VAT validation API when you need a specific national source. The other half of the job is keeping evidence: storing the result of each check — when it ran, what came back, and which source answered — so you can show your work later. Auditors on intra-EU supplies may ask for it; a lightweight record such as the VIES consultation number alongside your own logs is the kind of trail that holds up.

If you're building this in, the API documentation covers the request and response shape, and pricing has the plan limits. You can get a free API key and validate against VIES from your own code.

FAQ

What is a VAT ID?

A VAT ID is the number a tax authority assigns to a business when it registers for value-added tax. It identifies that business for VAT purposes and is used on invoices and in intra-EU trade. Across the EU it takes the form of a two-letter country prefix followed by a country-specific string of characters.

Is a VAT ID the same as a VAT number?

Yes. "VAT ID", "VAT number", and "VAT registration number" all refer to the same identifier — the number that identifies a business for VAT. The different names are just wording; they point at the same value on your invoices and in VIES.

What is the difference between a VAT ID and a tax number?

A VAT ID identifies a business specifically for VAT and, in the EU, carries a country prefix so it works across borders. A local tax number (or company registration number) identifies the business to the domestic tax office or company register for other purposes. They are issued for different reasons and are usually different values, so they are not interchangeable on an intra-EU invoice.

How do I check if a VAT ID is valid?

For EU VAT IDs, validity is confirmed against VIES, the European Commission's system that routes the query to the relevant national database; some numbers are cross-checked against national registries. Note that a correct format is not the same thing as a registered, active number — only a live check confirms that. You can run a one-off check with a free VAT number checker.

Do I need a VAT ID to sell in the EU?

It depends on your situation — where you're established, what and to whom you sell, and whether you cross a registration threshold. Some businesses are required to register for VAT and some are not, and the rules differ by member state. This is not tax advice; check your national tax authority's guidance or a qualified advisor for your specific case.

What is the format of an EU VAT ID?

An EU VAT ID is a two-letter country prefix followed by up to roughly 12 alphanumeric characters, with the exact pattern set by each country. The prefix is the country code — for example Greece uses EL rather than GR, and Northern Ireland uses XI. A German VAT ID looks like DE123456789.

Check any EU VAT number free

Confirm a single VAT ID against VIES in seconds with the free VAT number checker. Validating VAT IDs in your app instead? Get a free API key and call the VIES API from your own code — free plan, 100 requests/month.