How to Check a UK VAT Number?

Receiving an invoice with a VAT number on it does not automatically mean that the number is legitimate. Fake VAT numbers are more common than most businesses realise. Accepting one without checking can leave you unable to reclaim VAT, expose you to HMRC scrutiny, and, in serious cases, implicate your business in fraud.

This guide explains exactly how to check a UK VAT number, why it matters, and what to do when something does not look right.

What Is a UK VAT Number and What Does It Look Like?

A UK VAT number is a unique identifier issued by HMRC to businesses registered for Value Added Tax. It confirms that a business is legally authorised to charge VAT on its goods and services. Every VAT-registered business in the UK must display its VAT number on all VAT invoices.

Standard UK VAT number format: A UK VAT number consists of nine digits, prefixed with the letters GB. The standard format looks like this:

GB 123 4567 89

Some businesses, particularly those operating within certain government sectors, may use a slightly different format. These include:

Since Brexit, UK VAT numbers and EU VAT numbers are entirely separate systems. A GB prefix confirms UK registration. EU VAT numbers use country-specific prefixes, for example, DE for Germany or FR for France. A UK business trading with EU suppliers will encounter both formats and should verify each through the appropriate system.

Why Checking a UK VAT Number Matters Before You Do Business

Checking a VAT number is not just a box-ticking exercise. It carries real legal and financial consequences for your business.

• Vat Reclaim Depends On A Valid Number: You can only reclaim input VAT on purchases if the VAT invoice you hold is genuine. If the VAT number on an invoice is invalid, HMRC can and does refuse input tax claims, even if you paid the VAT in good faith. The financial loss falls on you, not the fraudulent supplier.
• Fake Vat Numbers Are A Fraud Red Flag: Businesses that charge VAT without being registered are committing VAT fraud. By checking supplier VAT numbers, you protect your business from being drawn into fraudulent supply chains. HMRC takes a particularly dim view of businesses that fail to conduct basic due diligence.
• Due Diligence Is A Legal Expectation: HMRC expects businesses to take reasonable steps to verify that their suppliers are legitimate. Checking a VAT number is one of the simplest and most fundamental due diligence steps available. Failing to do so weakens your position significantly in any HMRC dispute.
• Contract and Credit Risk Management: Verifying a VAT number confirms that a supplier is a registered, trading business. This is a basic but important step in any supplier onboarding or credit risk assessment process.

A two-minute VAT number check can prevent months of costly disputes. Make it a non-negotiable step before processing any new supplier invoice.

Who Needs to Check a UK VAT Number and When?

VAT number verification is relevant to a broader range of businesses and situations than most people realise.

• Businesses Reclaiming Input Vat: Any VAT-registered business that reclaims input tax on purchases should verify supplier VAT numbers as part of their standard invoice processing procedure. A single invalid number can trigger a VAT inspection.
• Finance and Accounts Payable Teams: Anyone processing supplier invoices should check VAT numbers, particularly for new suppliers, high-value transactions, or suppliers whose invoices appear inconsistent or unusual.
• Accountants And Bookkeepers: Professionals preparing VAT returns for clients are responsible for the accuracy of those returns. Checking client supplier VAT numbers is a core part of responsible VAT return preparation.
• Businesses Are Onboarding New Suppliers: VAT number verification should be a standard step in every supplier onboarding process, alongside company registration checks and credit assessments.
• Exporters And Importers Trading With Uk Businesses: Overseas businesses trading with UK suppliers or customers may need to verify UK VAT registration status for invoicing, customs, and compliance purposes.

When To Check:

• Every time you receive an invoice from a new supplier
• When an existing supplier’s VAT number changes
• When an invoice seems inconsistent or unusually structured
• Before submitting a VAT return containing significant input tax claims
• During supplier due diligence reviews

If VAT compliance isn’t already built into your supplier processes, now is the time to change that. Contact Nephos today and let us help you establish a verification workflow that keeps your returns clean and your business protected.

How to Check if a VAT Number Is Still Active and Valid

There are two primary methods for checking a UK VAT number. Both are free, official, and accessible to any business.

Method 1: HMRC’s Online VAT Number Checker

HMRC provides a free online tool specifically for checking UK VAT numbers. It is the most direct and reliable method available.

Steps to use the HMRC VAT checker:

1. Visit the HMRC VAT number checker at: https://www.tax.service.gov.uk/check-vat-number/enter-vat-details
2. Enter the VAT number you want to verify, in full, including the GB prefix
3. Optionally enter your own VAT number to generate a consultation number as evidence of your check
4. The tool confirms whether the number is valid and currently registered

The consultation number generated is important. It serves as a timestamped record that you carried out the verification. Keep this for your records, it can be produced as evidence of due diligence in the event of an HMRC enquiry.

Method 2: The EU VIES System (for cross-border checks)

Since Brexit, the EU’s VIES (VAT Information Exchange System) no longer covers UK VAT numbers. However, VIES remains the correct tool for verifying EU VAT numbers when trading with European suppliers or customers.

For UK businesses that also hold EU VAT registration, for example, through trading in an EU member state, those EU numbers can be verified through VIES at: https://ec.europa.eu/taxation_customs/vies/

What the checker confirms:

Method 3: Contact HMRC Directly

If the online tool returns an unclear result or you need additional confirmation, you can contact HMRC’s VAT helpline on 0300 200 3700. HMRC can confirm whether a VAT number is valid and currently active. This is particularly useful for high-value transactions or situations where online verification is insufficient.

How to Spot a Fake or Invalid VAT Number

Not every invalid VAT number is the result of deliberate fraud, some are genuine administrative errors. Either way, knowing the warning signs helps you catch problems early.

• The Number Does Not Match The Standard Format: A valid UK VAT number has nine digits with a GB prefix. Any number that deviates from this format, wrong digit count, missing prefix, or unusual characters should be treated with immediate suspicion.
• The Number Fails The Hmrc Modulus 97 Check: UK VAT numbers are mathematically structured. The nine digits must satisfy a specific algorithm known as modulus 97. Some online VAT checkers run this calculation automatically. A number that fails modulus 97 is definitely invalid, regardless of what the supplier claims.
• The Business Name Does Not Match Registration Records: When you check a VAT number through HMRC’s tool and request business details, the name returned should match the name on the invoice. A mismatch between the registered business name and the invoicing entity is a serious red flag.
• The Supplier Cannot Produce a VAT Registration Certificate: Any legitimate VAT-registered business can provide a copy of its VAT registration certificate on request. Reluctance or inability to produce this document warrants further investigation.
• The Invoice Structure Is Inconsistent: Legitimate VAT invoices must include specific information, the supplier’s VAT number, the VAT rate applied, the VAT amount charged, and the invoice date. An invoice missing any of these elements, or presenting them inconsistently, should be verified before payment.
• Vat Is Being Charged Below The Registration Threshold: Businesses with taxable turnover below £90,000 are not required to register for VAT. A business charging VAT but unable to produce a valid registration number, or whose turnover appears to fall below the threshold, should be questioned directly.

Suspicious invoices and unverified suppliers carry real risk for your VAT returns. Speak to Nephos today and let our team help you build a verification process that catches problems before they reach HMRC.

What to Do If a VAT Number Fails Verification

A failed VAT number check requires a clear, documented response. Here is how to handle it correctly.

• Step 1: Do not process the invoice for VAT reclaim: Until the VAT number is verified as valid, do not include the VAT on that invoice in your input tax claim. Including unverified VAT on a VAT return creates a direct compliance risk.
• Step 2: Contact the supplier directly: Raise the issue with your supplier immediately. Request a corrected invoice with the correct VAT number, or ask them to provide their VAT registration certificate. A legitimate business will resolve this quickly and without resistance.
• Step 3: Recheck after receiving updated details: Once the supplier provides updated information, run the new VAT number through the HMRC checker again. Record the consultation number from this second check for your files.
• Step 4: Document everything: Keep a record of the original invoice, the failed verification result, your communication with the supplier, and the outcome. This documentation protects your business if HMRC ever questions the transaction.
• Step 5: Report suspected fraud to HMRC: If you believe a supplier is deliberately using a fake VAT number to charge VAT they are not entitled to collect, report this to HMRC through their fraud reporting service. You can report VAT fraud online at gov.uk/report-tax-fraud or by calling the HMRC fraud hotline on 0800 788 887.
• Step 6: Review other invoices from the same supplier: If one invoice contains an invalid VAT number, review all previous invoices from that supplier. Identify any input VAT already claimed and assess whether an amendment to previous VAT returns is required.

Acting promptly and documenting every step is what separates a minor supplier issue from a serious compliance problem.

Common Mistakes Businesses Make When Checking VAT Numbers

These errors are consistent across businesses of all sizes. Most are easily avoided with a simple process change.

• Never Checking At All: Many businesses assume that any invoice bearing a VAT number is automatically legitimate. This assumption is incorrect and costly. VAT number verification should be a standard step in every invoice processing workflow.
• Only Checking Once At Supplier Setup: VAT registration can be cancelled at any time. A supplier who was registered when you first checked may no longer be registered today. Periodic re-verification, particularly for high-value or high-frequency suppliers, is good practice.
• Not Recording The Consultation Number: The HMRC VAT checker generates a consultation number as evidence of your check. Many businesses run the check but fail to save this reference. Without it, you have no documented proof that due diligence was carried out.
• Accepting A Screenshot As Proof: A supplier providing a screenshot of their own VAT number check is not sufficient verification. Always run the check yourself through HMRC’s official tool. Only a check you conduct independently carries evidentiary weight.
• Confusing Uk And Eu Vat Numbers: Since Brexit, UK and EU VAT registration are entirely separate. A UK business cannot verify an EU VAT number through HMRC’s checker, and vice versa. Use VIES for EU numbers and HMRC’s tool for UK numbers.
• Ignoring Format Errors On Invoices: A VAT number presented without the GB prefix, with incorrect spacing, or with the wrong digit count should always be queried. These may be minor typographical errors, or they may indicate something more serious. Either way, they require clarification before the invoice is processed.
• Not Amending Vat Returns After Discovering Invalid Numbers: If you discover that a VAT number on a previously submitted return was invalid, you may need to amend that return. Leaving incorrect input tax claims uncorrected compounds your compliance risk over time.

If your VAT verification process has any of these gaps, the time to close them is now. Contact Nephos today and let us help you put a clean, documented compliance process in place before it becomes a problem.

Final Thoughts

Checking a UK VAT number takes under two minutes. The consequences of not checking can take significantly longer to resolve, particularly if HMRC disallows your input tax claims or opens a compliance investigation.

Build VAT number verification into your standard invoice processing workflow. Check every new supplier. Re-verify periodically. Record your consultation numbers. And if something does not look right, act on it immediately rather than hoping it will not matter.

For businesses handling large volumes of supplier invoices, or operating in sectors with higher fraud risk, such as construction, recruitment, and wholesale trading, among them, robust VAT verification is not just good practice. It is a necessary part of managing your tax compliance position.

FAQs

What Does A Uk Vat Number Look Like? 

A standard UK VAT number has nine digits preceded by the GB prefix. For example, GB 123 456 789. Government entities may use a twelve-digit format. Any number deviating from this structure should be verified immediately.

How Do I Check A Uk Vat Number For Free? 

Use HMRC’s free online VAT number checker at tax.service.gov.uk/check-vat-number/enter-vat-details. Enter the VAT number in full, and the tool will confirm whether it is currently valid and registered.

Can I Check Someone Else’s Vat Number? 

Yes. The HMRC VAT checker is publicly accessible. Any business or individual can verify any UK VAT number. You do not need to be VAT-registered yourself to use the tool.

What Happens If I Reclaim Vat On An Invalid Number? 

HMRC can disallow your input tax claim and require repayment of the VAT reclaimed, plus interest and potentially a penalty. You may also face a compliance investigation if HMRC considers that due diligence was not carried out.

Is It Illegal To Use A Fake Vat Number? 

Yes. Issuing invoices with a fake or invalid VAT number to charge VAT is a criminal offence. It constitutes VAT fraud and can result in prosecution, significant financial penalties, and imprisonment.

How Often Should I Verify Supplier Vat Numbers? 

Verify every new supplier before processing their first invoice. For established suppliers, re-verify annually or whenever you receive a new invoice that looks inconsistent. High-value or high-frequency suppliers warrant more regular checks.

Can I Verify A Vat Number By Phone? 

Yes. You can contact HMRC’s VAT helpline on 0300 200 3700 to verify a VAT number verbally. This is useful when the online tool returns an unclear result or when additional confirmation is required for a high-value transaction.

What Is A Vat Consultation Number? 

A consultation number is a reference generated by HMRC’s online VAT checker when you verify a number. It serves as timestamped evidence that you carried out the check. Always save this reference, it is your proof of due diligence.