# Austria VAT number format

Source: https://veriport.io/vat-number-format/at (published 2026-10-28)

An Austria VAT identification number is the prefix AT followed by U + 8 digits; ATU13585627 is a well-formed example. The national check digit is public, so a mistyped number is caught before VIES is asked. Structure as published in the Commission’s VIES FAQ, consulted 2026-10-24.

## Structure

Prefix `AT`, then U + 8 digits. The regular expression the API applies to the part after the prefix is `^U[0-9]{8}$`; letters are upper-cased and spaces, dots and dashes removed before the test.

| Country prefix | Structure | Example | Public check digit |
|---|---|---|---|
| AT | U + 8 digits | ATU13585627 | yes, verified before VIES |

## The check digit

Austria publishes the algorithm of its check digit, so an impossible number is refused before VIES is asked: the answer says `structure.checksum: "failed"`, costs nothing and reaches no upstream. The same algorithms are implemented by the open libraries (jsvat, python-stdnum).

## How to validate it

The structure says whether a string can be an Austria VAT number; only VIES says whether it is registered. The free check below asks VIES live and shows the registered name and address where Austria publishes them; the API does the same from your code.

```bash
curl "https://veriport.io/api/v1/vat/validate?number=ATU13585627"
```

## What a valid answer proves

That the number was registered for intra-EU trade at the moment of the check. Keep the date and, on paid tiers, the VIES consultation number: together they are the evidence a tax audit asks for when an intra-EU supply was zero-rated.

## Questions

### How many digits does an Austria VAT number have?

U + 8 digits, after the two-letter prefix AT: ATU13585627 is an example.

### Is ATU13585627 a real VAT number?

It is a well-formed example used in the documentation; whether it is registered today is VIES’s answer, not this page’s. Check it with the free tool.

## Read next

- [VAT number formats of every member state](https://veriport.io/vat-number-format)
- [Free VAT number check](https://veriport.io/tools/vat-number-check)
- [The VAT validation API](https://veriport.io/vat-validation-api)
- [VAT rates in Austria](https://veriport.io/vat-rates/at)
- [Austria IBAN format](https://veriport.io/iban-format/at)

## Sources

- VIES — VAT Information Exchange System: FAQ and VAT number structures (Q11) — https://ec.europa.eu/taxation_customs/vies/#/faq (2026-10-24)
- VIES REST API — check-vat-number, check-status (technical information) — https://ec.europa.eu/taxation_customs/vies/#/technical-information (2026-10-24)