Österreich · Firmenbuchnummer
Firmenbuchnummer Checker
Look up an Austrian Firmenbuchnummer (FN) in the commercial register and see the company name, address, legal form and status.
What is a Firmenbuchnummer?
A Firmenbuchnummer (FN) is the number that identifies a company in Austria’s commercial register, the Firmenbuch — for example FN 93363z for OMV Aktiengesellschaft. It is up to six digits and a check letter, must appear in the company’s imprint and on its business letters, and is not the UID (VAT) number or the Steuernummer.
Firmenbuchnummer format
Up to six digits and a lowercase check letter.
(optional)
(up to 6 digits)
Example: FN 93363z (OMV Aktiengesellschaft, as printed in its imprint next to its UID ATU14189108).
- Input: With or without “FN”, spaces or a hyphen, in upper or lower case; leading zeros are dropped.
- Check letter: Not officially published. A wrong letter comes back as not found.
- What we return: Company name, address, legal form and status.
- Not an FN: The UID-Nummer (ATU + 8 digits), the 9-digit Steuernummer and the EU register ID (ATBRA.…).
How to check a Firmenbuchnummer
- 1 Find the FN in the company’s imprint (Impressum), letterhead or order form.
- 2 Enter it above, with or without “FN”. The checker looks it up in the commercial register.
- 3 Compare the returned name and address with the company you are dealing with.
- 4 For Austrian VAT rules, see our Austria VAT guide.
Frequently Asked Questions
What does a Firmenbuchnummer look like?
Up to six digits followed by a lowercase check letter — for example FN 93363z for OMV Aktiengesellschaft. “FN” is only a label; companies usually print it together with the register court, such as Handelsgericht Wien.
What is the difference between the Firmenbuchnummer, UID-Nummer and Steuernummer?
The Firmenbuchnummer identifies a company in the commercial register (Firmenbuch). The UID-Nummer is the VAT number, ATU plus 8 digits, issued by the tax office, and the Steuernummer is the 9-digit domestic tax account number. OMV, for example, has FN 93363z and UID ATU14189108. Check a UID-Nummer.
Where do I find a company’s Firmenbuchnummer?
In its website imprint (Impressum) and on its business letters and order forms: the Austrian Commercial Code (UGB § 14) and the E-Commerce Act (ECG § 5) require the Firmenbuchnummer together with the register court.
Does every Austrian business have a Firmenbuchnummer?
No. Companies and the other legal forms listed in the Firmenbuch Act are registered. Sole traders must register only once their turnover passes the UGB threshold (more than €700,000 in two consecutive years, or more than €1 million in one year), and freelancers and farmers are exempt even then; smaller sole traders can register voluntarily.
How is the check letter calculated?
The method is not officially published. Every real number we tested fits a weighted mod-17 rule, but only a register lookup is conclusive — a wrong letter comes back as not found.
Why does a real-looking Firmenbuchnummer show as not found?
Usually because the check letter is wrong or the company has been deleted. Deleted companies stay in the commercial register marked as deleted (gelöscht), but this checker currently reports them as not found.
Last reviewed: , against official sources.
Verify Austrian companies at scale
Check Firmenbuchnummern and UID numbers through one API — with the registered name and address.