What this message means
Some countries require your VAT refund claim to be submitted as an XML file that follows a strict, country-specific format. Before VAT4U hands you that file, it checks the claim data against the official format for that country.
If something doesn't fit - a field is empty, a value is in the wrong shape, or a character isn't allowed - you'll see a "We found issues with your claim data" screen instead of your download. This isn't a failure of your claim itself; it means one or more fields need a small correction before the file can be generated.
What's on the screen
Errors - the specific validation messages produced by the format check. These can look technical, but each one points to a real field in your claim data.
How to resolve - guidance to help you fix the issue, including:
An "Explain using AI" button. Click it and VAT4U will read the errors together with your claim data and give you a plain-English explanation: which expense or invoice is affected, what exactly is wrong with it, and how to correct it.
A list of common causes seen across claims, as a quick first check even before you use the AI explanation.
Common causes
A mandatory field is empty (for example, a required selection wasn't made before downloading - some countries need you to confirm a setting, such as a submission language, before the file is generated).
The Vendor VAT number isn't formatted correctly - it should generally contain the country code followed by digits only, with no spaces or extra characters.
A date is in the wrong format or outside an expected range.
The text contains unsupported characters, such as emojis or special/control characters copied in from a document.
Applicant or bank details on the claim don't match what's on file with the relevant tax administration or registration.
How to fix it
Open the Explain using AI panel first - it will usually point you straight to the affected invoice and field.
2. Go to the expense or invoice named in the explanation and correct the field mentioned (formatting, missing value, unsupported character, etc.).
3. If the issue involves a claim-level setting rather than a specific expense (for example, a selection you make just before downloading), go back one step in the submission flow, make sure that selection is set, and generate the file again.
4. Once corrected, retry generating the XML file from the claim's Submission tab.
If the issue persists
If you've corrected the data and the same error keeps appearing, or the AI explanation doesn't resolve it, contact support with your claim number - we'll take it from there.