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Slovenia VAT number format

A Slovenia VAT identification number is the prefix SI followed by 8 digits; SI50223054 is a well-formed example. The national check digit is public, so a mistyped number is caught before VIES is asked. Structure as published in the Commission’s VIES FAQ, consulted 2026-10-24.

Structure

Prefix SI, then 8 digits. The regular expression the API applies to the part after the prefix is ^[0-9]{8}$; letters are upper-cased and spaces, dots and dashes removed before the test.

Country prefixStructureExamplePublic check digit
SI8 digitsSI50223054yes, verified before VIES

The check digit

Slovenia publishes the algorithm of its check digit, so an impossible number is refused before VIES is asked: the answer says structure.checksum: "failed", costs nothing and reaches no upstream. The same algorithms are implemented by the open libraries (jsvat, python-stdnum).

How to validate it

The structure says whether a string can be a Slovenia VAT number; only VIES says whether it is registered. The free check below asks VIES live and shows the registered name and address where Slovenia publishes them; the API does the same from your code.

curl — validate SI50223054 on VIES
curl "https://veriport.io/api/v1/vat/validate?number=SI50223054"

What a valid answer proves

That the number was registered for intra-EU trade at the moment of the check. Keep the date and, on paid tiers, the VIES consultation number: together they are the evidence a tax audit asks for when an intra-EU supply was zero-rated.

Questions

How many digits does a Slovenia VAT number have?
8 digits, after the two-letter prefix SI: SI50223054 is an example.
Is SI50223054 a real VAT number?
It is a well-formed example used in the documentation; whether it is registered today is VIES’s answer, not this page’s. Check it with the free tool.

Free: VIES asked live, the answer dated and sourced.

Check a VAT number

Sources