Austria VAT number (UID / ATU)
Austria's VAT identifier uses the distinctive ATU prefix (not just AT) followed by 8 digits. The U in ATU stands for Umsatzsteuer — the German word for sales tax — and the final digit is a weighted modulo-11 control.
This page covers the VAT identifier for AT. The information below includes the correct format, checksum algorithm, entity types, and where to locate the number on documents. Use the full VAT validator to run a live check against these rules.
For active registration status — whether a specific number is currently registered and trading — the only authoritative source is VIES (European Commission). Format and checksum checks only validate the number's structure.
ATUse the Open VAT format database for the full regex pattern, character classes, and length rules for this country alongside all 27 EU members.
VAT-Scan implements the full checksum for AT. The validator will return a clear pass or fail result along with the expected control value, so you can see exactly what went wrong if the number is invalid.
See the Checksum methodology page for a detailed explanation of the algorithm families used across EU VAT numbers, including the algorithm used by AT.
- Entering the domestic tax number instead of the EU VAT identifier (they are sometimes different).
- Including or omitting separators — VAT-Scan normalises these automatically, but some systems do not.
- Treating a checksum pass as confirmation of active registration — always verify via VIES for B2B due diligence.
- Using the wrong prefix — for example, entering a number without the country code prefix at all.
Verification: VIES (European Commission) →