Slovenia · SI
The Slovenian VAT number
Eight digits that are the company’s tax number — and that cannot be derived from its registration number, even though the whole business register is published for free.
Format: SI + 8 digits
Example: SI33840890
Issued by: the Financial Administration (FURS), on VAT identification.
The format
A Slovenian VAT number always carries eight digits after the prefix. They are the company’s tax number, unchanged.
- SIThe country code.
- 3384089Seven digits of the tax number.
- 0The check digit.
The check digit is computed modulus 11 with weights 8, 7, 6, 5, 4, 3, 2. The first digit is never 0 or 1 — tax numbers start at 10000000.
Tax number, registration number, VAT ID
Slovenia runs two numbers that are constantly confused.
The matična številka (registration number) is 7 digits, or 10 for a branch, and is assigned by AJPES when the entity enters the business register. The davčna številka (tax number) is 8 digits and comes from FURS. Nothing computable links them.
The VAT identification number is the tax number with SI in front, but it exists only if the taxpayer is identified for VAT purposes. Every business has a tax number; not every business is VAT registered.
This is the Slovenian obstacle. AJPES publishes the entire business register free and openly — but the extract carries the registration number, not the tax number. So no row can be reached by a VAT number until FURS’s list of VAT-registered taxpayers is joined in.
Finding the company
AJPES
AJPES keeps the business register and publishes it as open data: name, seat, legal form, activity, annual reports. It is searched by name or registration number.
FURS
FURS publishes the list of taxpayers identified for VAT. Only that list connects a tax number to a company — and only the two sources together make a lookup by VAT number possible.
VIES
Slovenia discloses the name and the address through VIES. The address comes on one line with the postcode and town at the end, and the name is sometimes very short, because the registered abbreviation is published rather than the full legal name.
Slovenia-specific pitfalls
- The registration number is not the tax number. One comes from AJPES, the other from FURS, and no calculation links them.
- A tax number is not yet a VAT ID. Every taxpayer has one; VAT identification is a separate step.
- The
SIprefix is not part of the tax number. Domestically it is eight digits; on an EU invoice it isSIplus eight digits. - The name in VIES may be an abbreviation, so matching it back against AJPES by name often fails.
- The AJPES open data alone is not enough to look a company up by VAT number.
One API for 27 member states
Vatlas turns a European VAT number into a company record: legal name, national identifier, legal form, status and address. Same call, same shape, for Slovenia and for the other twenty-six.
curl "https://api.vatlas.dev/v1/vat/SI33840890" \
-H "Authorization: Bearer $VATLAS_KEY"Response:
200 OK
{
"data": {
"vatNumber": "SI33840890",
"countryCode": "SI",
"nationalNumber": "33840890",
"nationalId": null,
"name": "KI",
"legalForm": null,
"status": "active",
"address": {
"line1": "HAJDRIHOVA ULICA 19",
"line2": null,
"postalCode": "1000",
"city": "LJUBLJANA",
"country": "SI"
}
},
"meta": {
"origin": "vies",
"source": "VIES",
"sourceUpdatedAt": "2026-08-28T10:17:10.023Z",
"checked": ["database", "VIES"]
}
}meta.origin says where the answer came from: database for a register imported locally, source for a national API queried live, vies as a last resort. The shape of the response never changes from one country to the next.
Free to try. An email address creates an account — no credit card, no sales call — with 100 requests a month and a working key in about a minute.
Frequently asked
The Slovenian VAT number in short
How many digits does a Slovenian VAT number have?
Eight after the SI prefix — ten characters in total.
Are the tax number and the VAT ID the same?
The digits are. The VAT ID is the tax number with SI in front, but it exists only once the taxpayer is identified for VAT.
What is the difference between the registration number and the tax number?
The registration number is assigned by AJPES on entry in the business register and has seven digits. The tax number comes from FURS and has eight. Neither can be computed from the other.
Why does VIES reject an existing Slovenian company?
Because it is not identified for VAT. It has a tax number but no VAT identification.
Can I download the whole Slovenian business register for free?
Yes, AJPES publishes it as open data — but keyed by registration number rather than tax number, so it cannot be searched by VAT number on its own.
VAT numbers in other countries
Last updated 28 August 2026.