Frontendplace Blog

In Februari 2014 all incasso payments must be done with the IBAN bank account numbers and all the webshops should consider the impact of these changes. All the banks and insurance companies already are migrating now.

So I would like to give some information here about some technical information for programmers that need to validate the numbers when updating payment software.

IBAN (International Bank Account Number) is an international standard for bankaccount numbers.(ISO13616) . The number consist of the following parts:

• ISO countrycode;
• Checksum number;
• Bankidentity;
• Bankaccountnumber at the local bank;

The IBAN starts with two country characters and two checksum digits
The IBAN is maximum 34 characters in length. The Bank identity and Bank accountnumber together is the BBAN. Each country has its own pattern of BBAN.

The Dutch IBAN is 18 character long and looks like this:

The Dutch bankidentity consists of 4 letters of the BIC code of the bank where the account is held.

Examples:

NL05 INGB 0661 0950 88
NL91 ABNA 0417 1643 00
NL54 RABO 0387 7819 00

So how do you need to check  the IBAN

The IBAN check is done by converting the number first by placing the country code and checksum at the end of the string value, replacing all characters with numbers (A=10, B=11 etc) and performing a BBAN test and Mod97 test. The resulting remainer should be 1.

Before the validation starts all spaces need to be removed and the characters are capitalized.
The following checks can be done:

• The code is not longer than 34 characters
• The IBAN contains only a-z, A-Z, 9-0
• The first characters must be: letter letter digit digit
• The check digits of IBAN cannot be 00,01 or 99.
• The length of IBAN is checked according to the country BBAN.
• The country structure of IBAN is checked according to the country BBAN.
• A Mod97 test (ISO7064) is performed on a ISO13616 prepared IBAN digitstring.