# Austria IBAN Validator & Bankleitzahl Checker (OeNB)
> Instant MOD-97 validation for 20-character Austrian IBANs with 5-digit Bankleitzahl (BLZ) and 11-digit account number extraction.

- **Canonical URL:** https://stanzaapi.com/tools/iban-validator/country/austria-at
- **Governing Standard:** ISO 13616 / ISO 7064 MOD-97-10 (SWIFT & ISO 13616 IBAN Registry)
- **Latency:** <1ms Edge
- **Privacy:** In-memory execution only (zero data stored or logged)

## Technical Overview & Governing Rules
In Austria, the International Bank Account Number (IBAN) has a fixed length of 20 alphanumeric characters starting with the two-letter ISO 3166-1 alpha-2 country code 'AT', followed by two MOD-97 check digits.

The National Basic Bank Account Number (BBAN) follows the official pattern: 16n. The national bank code is located at BBAN character offset [0:5].

National IBAN transfers in Austria (AT) are settled in EUR.

Validation computes the ISO 7064 Modulo-97-10 checksum by transposing the first 4 characters to the end, converting letters to numeric digits (A=10, ..., Z=35), and calculating arithmetic integer modulo 97 (must equal 1).

An Austrian IBAN is exactly 20 characters: AT, two MOD-97 check digits, a 5-digit Bankleitzahl (BLZ), and an 11-digit account number (structure AT2!n5!n11!n).

## Specification Matrix
| Attribute | Value | Description |
| --- | --- | --- |
| Country Code | AT | ISO 3166-1 alpha-2 |
| Total IBAN Length | 20 characters | Fixed standard length |
| BBAN Format | 16n | National structure (n=numeric, a=alpha, c=alphanumeric) |
| SEPA Zone | Yes (Single Euro Payments Area) | SEPA compliance status |
| Currency (ISO 4217) | EUR | National settlement currency |
| Bank Code Position | BBAN Offset 0 (5 chars) | National clearing code |
| Branch Code Position | N/A | Branch identification |
| Bankleitzahl (BLZ) | BBAN offset 0 (5 digits) | Austrian bank routing code, published in the OeNB bank code register |

## Standard JSON Response Model
```json
{
  "valid": true,
  "iban": "AT611904300234573201",
  "countryCode": "AT",
  "countryName": "Austria",
  "length": 20,
  "bban": "16n",
  "sepa": true,
  "checksumValid": true,
  "bankCode": "XXXX"
}
```

## Frequently Asked Questions & Edge Cases
### Q: How many characters is an IBAN in Austria?
**A:** An official IBAN in Austria (AT) is exactly 20 characters in length. Any shorter or longer value fails ISO 13616 validation.

### Q: Is Austria part of the SEPA payment network?
**A:** Austria is a member of the Single Euro Payments Area (SEPA), enabling low-cost euro bank transfers.

### Q: What currency are Austria IBAN transfers settled in?
**A:** IBAN transfers for Austria (AT) settle in EUR, the national settlement currency. Cross-border SEPA transfers to Austria may still be denominated in EUR where both banks support the scheme.

### Q: How is the MOD-97 check digit calculated for AT IBANs?
**A:** The first 4 characters are moved to the end, letters are converted to numbers (A=10 to Z=35), and the resulting number is evaluated with modulo 97 arithmetic. A valid IBAN yields a remainder of exactly 1.

### Q: What is a Bankleitzahl (BLZ) in an Austrian IBAN?
**A:** The Bankleitzahl is the 5-digit Austrian bank routing code. In an Austrian IBAN it sits immediately after AT and the two check digits, followed by the 11-digit account number; the BLZ is published in the Oesterreichische Nationalbank bank code register.