Austrian UID / ATU
Generator
Generate valid Austrian VAT numbers (UID / ATU) that pass the official BMF checksum algorithm — for software testing and development, entirely in your browser.
About Austrian UID / ATU
The Umsatzsteuer-Identifikationsnummer (UID), characterized by the prefix ATU, is the Austrian Value Added Tax (VAT) identification number for businesses.
It is mandatory for cross-border EU trade (VIES validation), electronic invoicing, and domestic corporate billing.
Austrian UID / ATU Anatomy
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 3 | Prefix | 3 chars | Fixed "ATU" (Austria VAT) | ATU |
| 4 to 10 | Company Serial | 7 digits | Registration sequence with the Federal Ministry of Finance | 1234567 |
| 11 | Check Digit | 1 digit | Calculated using a modified Luhn algorithm with a +4 constant | 5 |
Official Austrian ATU Algorithm
| Step | Description |
|---|---|
| 1. Take the 7 digits | Take the 7 numeric digits that follow the ATU prefix. |
| 2. Sum the odd-position digits | Sum the digits at positions 1, 3, 5, 7 (1-indexed) as-is. |
| 3. Double and reduce the even positions | Multiply the digits at positions 2, 4, 6 by 2, and if the result is 10 or more, add its digit sum instead. |
| 4. Add the constant | Add the fixed constant +4 to the accumulated total. |
| 5. Compute the check digit | The check digit is (10 − (Sum mod 10)) mod 10, which must match the 8th digit. |
Frequently Asked Questions (FAQ)
Why does it always start with ATU?
"AT" is Austria's ISO country code and "U" stands for Umsatzsteuer (VAT) — the Austrian tax authority fixed this exact 3-letter prefix for every VAT number it issues, unlike most EU countries which use just their 2-letter ISO code.
What is the difference between Swiss and Austrian UID?
They share the "UID" name but are unrelated formats from different tax authorities: Switzerland's UID (CHE-xxx.xxx.xxx) is a general business identifier issued domestically and isn't an EU VAT number, while Austria's UID (ATU + 8 digits) is specifically the Austrian EU VAT identification number, validated through the EU's VIES system.
Are the generated numbers official or real?
No. The numbers generated here are synthetic test data that satisfy the official BMF checksum used by the UID/ATU format, for software development and QA testing only. They are not issued by the BMF, are not linked to any real company, and must never be used on real invoices or official filings.