An invalid result when validating a VAT number can be frustrating, especially when your customer insists their number is correct. This guide walks through the most common causes of invalid results and provides systematic troubleshooting steps to resolve the issue. Understanding why validation fails helps you determine whether there is a genuine problem or a resolvable technical issue.
Before investigating further, run through this quick checklist. These simple issues cause most validation failures:
If the number passes all these checks and still shows invalid, continue with the detailed troubleshooting below.
The most frequent cause of invalid results is simply entering the number incorrectly. Even small errors prevent validation.
Solution: Request the exact VAT number from your customer as it appears on their official VAT registration certificate. Copy it exactly, then remove any formatting characters before validation. Compare character by character with what you entered.
Newly registered businesses may not appear in VIES immediately. National databases update at different intervals, and some countries are slower than others. A business may have received their VAT number but not yet be searchable through VIES.
Solution: Ask the customer when they received their VAT registration. If within the last few weeks, the delay may be normal. Request a copy of their VAT registration certificate as alternative documentation. Retry validation after a few days. For persistent issues, the customer should contact their national tax authority to verify their VIES activation status.
Some EU countries require separate registration for intra-community transactions. A business may have a valid domestic VAT number that is not activated in VIES because they have not requested intra-community registration.
Solution: This is particularly common with Spanish VAT numbers. Ask the customer to confirm they are registered in their country's ROI (Register of Intra-Community Operators) or equivalent. They may need to submit a specific request to their tax authority to be added to VIES. Until resolved, you may need to charge VAT on supplies to that customer.
VAT registrations can be cancelled for various reasons: business closure, falling below registration thresholds, administrative deregistration for non-compliance, or merger with another entity. A number that was valid in the past may no longer be active.
Solution: If you previously transacted with this customer successfully, the status change may be recent. Ask the customer directly about their current VAT registration status. If they claim to still be registered, they should verify with their tax authority and obtain current documentation.
Sometimes the national database for a specific country is temporarily offline, returning invalid results for all numbers from that country. This differs from the explicit "service unavailable" message—some implementations return invalid when they cannot connect.
Solution: Try validating a different number from the same country (you can use your own VAT number if you have one from that country, or try a well-known company). If multiple numbers fail, the national database may be experiencing issues. Wait a few hours and retry. Check the European Commission VIES website for any announced maintenance.
Since Brexit, UK VAT numbers starting with GB are not in VIES and cannot be validated through it. Many users still attempt to validate UK numbers through VIES and receive invalid results.
Solution: For UK VAT numbers (GB prefix), use the UK Government's VAT number checker at gov.uk instead of VIES. The exception is Northern Ireland businesses trading goods with the EU, who have XI-prefixed numbers that can still be validated through VIES.
Large organizations may have multiple VAT numbers for different legal entities or branches. The number your customer provides might belong to a related entity rather than the one you are trading with.
Solution: Verify the company name and address returned by validation matches your customer's details. If the customer is part of a group, confirm which legal entity is the contracting party and use that entity's specific VAT number.
Most VAT number formats include check digits that allow validation of mathematical correctness before querying the database. A number with incorrect check digits will fail even if the base number exists.
Solution: This usually indicates transcription error. Have the customer verify the number against their official documents and provide it again. A single wrong digit anywhere in the number can cause check digit validation to fail.
Germany uses two identification systems: the USt-IdNr (VAT ID starting with DE) and the Steuernummer (domestic tax number with regional format). Only the USt-IdNr can be validated through VIES. If a German business gives you a Steuernummer instead of a USt-IdNr, it will not validate. Ask specifically for their "USt-IdNr" or "Umsatzsteuer-Identifikationsnummer."
Spain requires businesses to register separately for intra-community operations through the ROI (Registro de Operadores Intracomunitarios). A Spanish business may have a valid domestic NIF that does not appear in VIES because they have not completed ROI registration. They need to request ROI activation through their local tax office.
French VAT numbers derive from the SIREN number with a two-character validation key. The key can be letters, numbers, or mixed, but excludes I and O. If a French number fails, verify the entire 13-character string (2-character key + 9-digit SIREN) is complete and correctly transcribed.
Dutch VAT numbers must include the B followed by two digits at the end (format: NL + 9 digits + B + 2 digits). The most common suffix is B01, but numbers B02 and higher exist for entities with multiple VAT registrations. Ensure the complete suffix is included.
Poland grants EU VAT numbers only after a business exceeds the threshold for intra-community acquisitions or specifically requests intra-community registration. Smaller Polish businesses may have valid domestic NIP numbers that are not in VIES.
If you have exhausted troubleshooting steps and the number still shows invalid:
Request documentation: Ask the customer for a copy of their VAT registration certificate or a recent letter from their tax authority showing their VAT number. This provides alternative evidence of VAT status even if VIES validation fails.
Contact their tax authority: If the customer believes they are properly registered, they should contact their national tax authority to verify their VIES status and request correction if needed. Tax authorities can investigate why a number is not appearing in VIES and fix database issues.
Proceed with caution: If you must proceed with the transaction despite validation failure, consider charging VAT at your domestic rate. The customer can reclaim this through their VAT return or the VAT refund procedure. This protects you from VAT liability if the number proves genuinely invalid while still completing the commercial transaction.
Document your attempts: Save records of your validation attempts, including dates, the number entered, and results received. If you proceed without successful validation, this documentation shows you made reasonable efforts to verify the VAT number, which may be relevant if questions arise later.
Minimize validation problems by establishing good practices:
