A VAT number on an invoice is a claim, and the reason to test it is money: if you reclaim input tax on an invoice from a business that was not registered when it issued it, the reclaim is not valid and the cost falls back on you. HMRC publishes a free service that answers the question directly, and it answers two different versions of it. This page sets out what each answer means, what the check does not tell you, and what to do about an invoice whose number will not verify.
The two answers HMRC's checker gives, and why the second one matters
HMRC's check a UK VAT number service takes a nine-digit number and tells you whether it is registered and, if the trader has consented, the name and address it is registered to. That second answer is the useful one. A number can be perfectly valid and belong to a different business from the one on your invoice, which is what an invoice-redirection fraud looks like from your side of it. Enter your own VAT number as well and the service returns a dated reference for the check, which is the record you want if the reclaim is ever questioned.
What the check proves, and the three things it does not
It proves the number exists and is registered today. It does not prove the business was registered on the date of the invoice you are holding, which is the date that actually decides your reclaim. It does not prove the person who sent you the invoice is the business the number belongs to. And it says nothing about whether the rate they charged is right for the supply: a valid registration and a wrong rate are entirely compatible, and the wrong rate is your problem too, because you can only reclaim VAT that was properly chargeable.
When a number will not verify
Check the obvious first: a UK VAT registration number is nine digits, and the GB prefix, spaces and punctuation that suppliers put on invoices are not part of it. If it still will not verify, ask the supplier for a copy of their registration certificate before you pay, and do not reclaim the VAT in the meantime. A newly registered business genuinely may not appear yet, because a trader who has applied but not received their number cannot show VAT on an invoice at all and is supposed to raise the invoice gross and reissue it later.
Questions people ask about check a uk vat number
Where can I check a UK VAT number for free?
On GOV.UK's own check a UK VAT number service. It is free, needs no account, and returns the registered name and address where the trader has consented to that being shown.
How do I check if a company is VAT registered when I only have its name?
There is no official search by company name. HMRC's service takes the number, not the name. Ask the supplier for the number, take it from an invoice or their website footer, then verify it and compare the name the service returns with the name on your paperwork.
Does a VAT registration number check protect my reclaim?
It helps and it is not a guarantee. Keeping a dated record of the check, which HMRC's service gives you when you enter your own VAT number too, is evidence you took reasonable care. The reclaim still depends on holding a valid VAT invoice for a supply that was properly chargeable.