This is the check whose omission can cost you directly — not because a partner fails to pay you, but because of what happens to an invoice they issue without a valid VAT identification.
What it is
The Slovenian Financial Administration can withdraw a VAT identification ex officio. The VAT Act provides for two situations: withdrawal because the taxable person has stopped trading or no longer meets the conditions, and withdrawal where the identification was abused or abuse was suspected.
Both lists are public and published by the authority as open data. Each withdrawal carries a date, so it is possible to see when the VAT number was obtained and when it ceased.
Why it matters
Only an entity identified for VAT may issue an invoice charging it. If a partner has had their identification withdrawn and charges VAT anyway, the tax is invalidly charged — and deducting the input VAT from such an invoice is contestable.
A withdrawal is also a signal in itself. Withdrawal for suspected abuse is the strongest negative signal readable free from Slovenian public data, and it often appears before anything else about the company becomes visible.
When to check
What counts is the position at the time of the supply, not when you first vetted the supplier. An identification can be withdrawn at any time.
So: before the first payment to a new supplier, and periodically for a regular one. For large supplies, before every payment — the lookup takes seconds.
What to do if it has been withdrawn
Check the number in VIES first: it tells you whether it is valid right now across the EU. If it is not, ask for a corrected invoice without VAT.
If the identification was withdrawn for suspected abuse, the question is wider than one invoice. Check also whether insolvency proceedings are running against the company and when its directors last changed — it is often the same story.
Why this article exists
Most foreign company-checking tools do not have this check, because it is not published in their country. In Slovenia it is: both lists are free, complete and dated, and together with the insolvency publications they are the most concrete risk you can read straight out of public data.