IBAN-Validation

How is an IBAN actually structured?

An IBAN in Germany consists of

To summarize it in a simple way:

We can't detect all wrong IBANs with our system, only those where e.g. a number mistake happened while typing or the basic format is not correct. The validation is somewhat better than e.g. with e-mail, where only the format is taken into account, nevertheless e.g. generated fake IBANs cannot be recognized as "wrong".

Therefore, our recommendation is: as often as possible to compare the IBAN with the bank card, we can also include a checkbox with the text "compared with bank card", which can also be mapped e.g. on the dashboard by a widget (% bank card compared - similar to opt-ins).

To describe it in more detail:

The IBAN consists of:  2-digit country code + 2-digit check digit + country-specific BBAN

The BBAN is a number of up to 30 digits, defined differently in each country, consisting of bank code and account number is just one of many examples.

Validated/detected as incorrect (offline): 
1. country code (valid and from one of the 78 registered IBAN countries)
2. wrong character e.g. 4234 instead of 1234. 
3. left/right offset
4. a large amount of 2 or more wrong characters (but not all)
5. IBANs of the QR-Bill Standard Switzerland & Liechtenstein

QR-IBANs are part of the QR-Bill standard. They can only be used for receiving money and are therefore also recognized as invalid by our system. For Switzerland, the first 5 digits of the BBAN identify the bank (in Switzerland the IID). The range for the QR-IBANS is between 30000 and 31999 (see 1.3.2 QR-IID).

However, the BBAN is more difficult to check, because at least one different algorithm is used for calculation in each country. In Germany, for example, a complex structure with 143 algorithms is used.