What Is a VAT Number? UK Format and Why Businesses Need One

What is a VAT number?

A VAT number is the unique reference HMRC gives a business when it registers for VAT. A UK VAT number is GB followed by nine digits, written as GB123456789 or GB 123 4567 89.

It is also called a VAT registration number, a VAT ID or a VAT reg number. These all mean the same thing.

A business must show its VAT number on every VAT invoice it issues. Its VAT-registered customers need that number to reclaim the VAT on the invoice.

UK VAT number format and examples

A standard UK VAT number has three parts:

The GB prefix is often left off within the UK, for example 123 4567 89. Include it on invoices to customers outside the UK.

How many digits is a VAT number?

Nine digits for a standard UK business, and twelve for a branch trader. The two letters at the front are a country prefix, not part of the number.

If a number has a different number of digits, it is probably a different reference. Company numbers, UTRs and EORI numbers are often mistaken for VAT numbers.

VAT number vs company number vs UTR vs EORI

A VAT-registered business's EORI number is usually GB, its nine-digit VAT number and 000, which is why the two get confused. They are not interchangeable.

Where to find your own VAT number

1. Your VAT registration certificate, which HMRC sends when you register
2. Your HMRC business tax account, in the VAT section
3. Any VAT invoice you have already issued
4. Letters from HMRC about your VAT

If you have lost your certificate, you can view it in your HMRC business tax account.

How to find another company's VAT number

There is no public register of UK VAT numbers that you can search by company name, and Companies House does not hold VAT numbers. You need to get the number from the business, then check it.

• Look at an invoice or receipt the business has given you. A VAT-registered business must show its VAT number on its VAT invoices.
• Check the footer of its website, or its terms and conditions.
• Ask the business. A VAT number is not confidential.
• Then check the number with the VAT number checker above or the GOV.UK service.

How to check whether a VAT number is valid

Use GOV.UK's Check a UK VAT number service. It confirms whether the number is registered and shows the business name and address HMRC holds. Our checker above tells you straight away whether a number is in a valid format.

For XI (Northern Ireland) numbers and EU VAT numbers, use the European Commission's VIES service. For a full walkthrough, see how to check a UK VAT number on GOV.UK and VIES.

Get proof that you checked. If you enter your own VAT number on GOV.UK as well as the one you are checking, HMRC gives you a consultation number. Keep it with the date. It is your evidence that you checked the number.

Why it matters. If you reclaim VAT on an invoice with an invalid VAT number, HMRC can refuse the claim, and the cost falls on you, not the supplier. Check every new supplier before you pay its first invoice.

The check digit: how VAT numbers validate themselves

A UK VAT number contains its own check, so many typing mistakes can be spotted without contacting HMRC.

Multiply the first seven digits by 8, 7, 6, 5, 4, 3 and 2 in turn, and add the results. Add the last two digits of the number to that total. For a valid number, the result divides exactly by 97. Newer numbers use the same method with 55 added to the total first.

This only proves the number is well formed. It does not prove it belongs to the business using it, so you still need the GOV.UK check.

Do you need a VAT number?

You must register for VAT, and you get a VAT number, if your taxable turnover goes over £90,000 in any rolling 12 months, or you expect it to go over £90,000 in the next 30 days alone.

You can also register voluntarily below the threshold. That often suits a business whose customers are VAT registered, because they can reclaim the VAT you charge and you can reclaim VAT on your costs. It rarely suits a business that sells to the public.

A business that is not VAT registered has no VAT number and must not charge VAT. See when to register for VAT for the full rules.

Just got your VAT number? What to do next

From your effective date of registration, which is on your registration certificate, you must:

• Charge VAT at the right rate on your sales
• Show your VAT number on every VAT invoice
• Keep digital records of your sales and purchases
• File a VAT return, usually every three months, through software that works with Making Tax Digital
• Pay any VAT you owe by the deadline, usually one month and seven days after the end of each period
• Tell HMRC if your business details change

Making Tax Digital applies from your first VAT return. There is no turnover exemption. Your first return can cover a longer or shorter period than three months, so check its dates in your business tax account or read our guide to your first VAT return after registration.