The issue
If you upload your claim attachments as a ZIP file created on a Mac, you may notice that after processing, VAT4U shows two PDF files instead of the single file you uploaded:
• Your original file (e.g. 21609 CLAIM_attachments_Final.pdf)
• A second, much smaller file with the same name but starting with a dot (e.g. ._21609 CLAIM_attachments_Fina.pdf)
Because both files were included in your ZIP, both get uploaded and both are sent through to the tax portal. The dot-file is not a real document — it cannot be opened, and on the tax administration's side it may appear as a second, broken attachment alongside your real one, as shown below.
Why this happens?
This is not a VAT4U specific issue. It happens because of how macOS creates ZIP archives. When you compress a file on a Mac using the built-in “Compress” / “Archive” option (right-click → Compress), macOS automatically adds a second, hidden file to the ZIP alongside your original one. This hidden file's name starts with a dot (e.g. “._filename.pdf”) and contains only metadata that macOS uses internally (such as zoom level or the last page you had open) - it is not a usable document and was never meant to be opened.
Because this hidden file is bundled inside the ZIP, it gets uploaded to VAT4U together with your real file, and is then included when the claim is submitted to the tax authority.
What you'll see in VAT4U
In the Attachments tab you can find the genuine file and the hidden “dot file” created by macOS, both uploaded from the same ZIP:
What you'll see on the tax portal
On the TAX administration's portal, the same two files appear — the second one cannot be opened:
What to do about it
To avoid this happening on your next claim, please follow these steps before uploading a ZIP file that was created on a Mac:
Open the ZIP file and check its contents before uploading it to VAT4U.
Look for any file names starting with a dot (for example, “._filename.pdf”) — these are the hidden macOS metadata files described above.
Remove these dot-files from the ZIP, keeping only your real, original document(s).
Re-compress the remaining file(s) and upload the cleaned ZIP to VAT4U.
Tip: If you only need to attach a single file, you can also upload the PDF directly without zipping it — this avoids the issue entirely.
If you've already submitted a claim with this issue
If a claim has already been submitted and you notice the extra, unreadable file in the Attachments tab or on the TAX portal, you can remove it directly in the TAX portal before clicking submit button.