Austrian VAT Number (UID / ATU)

Three different numbers get called a tax number in English. The UID is the VAT identifier; the Steuernummer is the file number the business is registered under, and the two are issued together.

The issuing authority is Finanzamt Österreich, the single national tax office (UStR 2000 Rz 4336).

The administrative guideline sets the format: the country code AT followed by one block of nine characters (UStR 2000 Rz 4343). Note 3 fixes what the nine are: always a "U" in the first position after the country code, and then eight digits. So the number is not nine digits, the question search engines report most often here: it is one letter and eight digits after AT, 11 characters in all.

The EUIPO table gives Austria the same structure and prints it ATU99999999. That is a mask, not a number: each 9 stands for any digit, and it could never be issued, because the last position is computed from the others. The U is fixed, and neither source glosses it, so neither does this page.

Partly, and the rule is published. The last digit is a check digit. The Ministry of Finance publishes the member states' construction rules, and the Austrian entry gives nine positions, C1 always the letter U, C2 to C9 numeric, and C9 computed from the earlier digits: Information über die Konstruktionsregeln der Umsatzsteuer-Identifikationsnummern (UID), Stand November 2020. Its first page records that the member states released these rules for publication, in the format the European Commission prescribes. The formula is there, and this page links it rather than reprinting it.

Now the half that matters more. A check digit tests the form of a number and nothing else. A string that passes it is well formed. It does not follow that it was ever issued, that it is valid today, that it has not been withdrawn, or that it belongs to the counterparty who wrote it on an invoice. Only the confirmation procedure under Art. 28 Abs. 2 UStG, or VIES, answers those. An offline check is worth one thing: it tells you a number is mistyped before you spend a query on it.

The statute is written as a duty rather than a power: the tax office "hat ... zu erteilen", it has to issue the number. Which column a business falls in depends on its turnover, not on its legal form.

A Kleinunternehmer below the small-business ceiling of EUR 55,000 net a year is exempt without the right to deduct input VAT (usp.gv.at, VAT overview, 1 January 2026), which puts it in the middle column; the regime is on the VAT guide. There the standard is lower and explicit: it is enough to make it credible that such transactions will be made in future (UStR 2000 Rz 4339).

In the ordinary case nobody applies for anything: the number comes off the tax-registration questionnaire, and the only question is which one.

The guideline's text for a written application dates from 2007 and still offers fax and telegram: the substance holds, the channel does not. Being taken onto the VAT register as a whole is a separate job: how to register for VAT in Austria.

No Austrian official source publishes a service standard or an average. The business service portal, the Ministry of Finance site, its form service and this project's archive of official texts were searched on 16 September 2026 and none of them states one, so this page states none. Any figure elsewhere is somebody's estimate.

What a reader can control is the file, not the clock: which questionnaire fits the legal form, whether a written application carries the name, the Firma, the address and the Steuernummer, and whether the business can show the entrepreneur status the next section is about.

The gate is not the company, it is entrepreneur status. Art. 28 Abs. 1 makes the issue mandatory, but its conditions run through § 2 UStG: an entrepreneur independently carries on an activity that is sustained (nachhaltig) and aimed at income, even without an intention to make a profit. Sustained means repeated, and the test is the outward appearance, the äußeres Erscheinungsbild (VwGH 9 November 1983, 81/13/0151).

In UFS Linz, 29 May 2008, RV/0324-L/08 the tax office refused a number on four grounds: what one office argued once, not a checklist to prepare against.

1. Only one customer. No participation in general economic dealings, the office argued, and that customer had been dissolved by a register entry of 1 June 2007 while the contract offered as proof still named it.

2. Language. A record of 21 March 2007 showed the applicant spoke only "etwas deutsch", some German, so legal transactions were said to be barely conceivable without an interpreter.

3. Vague invoicing. An invoice for "diverse Arbeiten", various works, allowed no specification, quantification or timing of the work supplied.

4. No input VAT claimed. The returns claimed no input VAT deduction, from which the office inferred that nothing had been bought at all.

The appeal succeeded. Grounds 2 to 4 do not touch entrepreneur status at all: "Weder schlechte Sprachkenntnisse, noch unklare Ausdrucksweisen in Rechnungen oder die vorläufige Nichtgeltendmachung von Vorsteuern berühren die Unternehmereigenschaft an sich." What established it was ordinary evidence: a subsisting trade licence, a VAT assessment of 12 July 2007 recognising turnover and input VAT, an invoice the next year for the same work, and written confirmations from two companies that wanted to keep placing orders. On that outward appearance the number was "zwingend zu erteilen".

One caution. The Unabhängiger Finanzsenat became the Bundesfinanzgericht in 2014 and no later decision was searched for, so read this as a decided case, not settled practice.

Yes, and again it is a duty rather than a power. The notice granting a UID must be taken back where the circumstances decisive for issuing it have changed, or where their existence was wrongly assumed (Art. 28 Abs. 1 UStG).

Validity can also be cut short. In the same case the tax office granted the UID by a notice of 7 September 2007 and, by a second notice of the same day, limited the validity of the number it had just issued to 8 September 2007. That limitation was set aside on appeal on 29 May 2008. The reader's own duty mirrors the same power: one calendar month to report a change in the decisive circumstances.

The number is not decoration. Three provisions decide when it belongs on the paper, and one decides whether a cross-border supply is exempt.

Since 1 January 2020 the exemption depends on a timely, complete and correct ZM, which is why the customer's number and the statement are one subject. Which ZM period applies follows the advance-return period, where EUR 100,000 of turnover is the line between the quarter and the month (§ 21 Abs. 2 UStG). Reverse charge itself and that regime belong to the VAT guide. Keeping the invoices and the statement in order is bookkeeping, which in Austria is reserved, with payroll, to licensed Bilanzbuchhalter and Steuerberater (BiBuG 2014 §§ 2 and 3, WTBG 2017 § 2 Abs. 1): bookkeeping services austria.

The number is one step of a registration, not the whole of it. What being taken onto the Austrian VAT register involves, and in what order, is on how to register for VAT in Austria. If the question is about your own company rather than the procedure, ask about your Austrian company.