Bank account number

The account number is a unique number that identifies each bank account. Payment transactions can be processed quickly and securely with the account number .

The account numbers are not assigned arbitrarily, but usually contain a check digit , i.e. H. an algorithm is used to calculate a further digit from a given number , which together with the given number forms the account number. Usually the check digit is at the end of the account number. For the international bank account number (IBAN), the checksum has two digits and is immediately after the country code , e.g. B. DE78.

Within a credit institution, additional organizational criteria are sometimes mapped in the account number. Examples of this are the number of the branch in charge of the account, which is often shown in the first digits of the account number, or a sub-account number (e.g. two digits at the end of the account number), which indicates whether it is a current account , savings or loan , Fixed-term deposit or escrow accounts , and which enables further electronic processing to forward payments to the correct subsequent systems.

Germany

In Germany , payment transactions are standardized by the data transmission agreement ; external account numbers consist of up to ten decimal digits. If necessary, filler zeros can be used for low account numbers . Together with the bank code , the account number enables a German bank account to be clearly identified.

Large banks in particular sometimes use longer periods in their internal systems - e. B. twelve-digit account numbers that contain the number of a main branch and with which the uniqueness can be achieved within the bank without storing the associated bank code.

The check digit calculation method is not uniform at German banks, there are currently 143 different methods that are defined for the individual bank sort codes.

The check digit calculation methods change at irregular intervals. As of June 6, 2011, the check digit calculation methods B8, C6 and D4 were changed. In addition, the new check digit calculation methods D7 and D8 became effective. Software that validates bank details must take into account the current check digit calculation methods.

Austria

In Austria up to eleven-digit account numbers and five-digit bank codes are used. As in Germany, there are institute-specific check digit calculation methods.

Switzerland

Account numbers in Switzerland have up to 16 digits. The length and any check digit calculation methods are inconsistent. Postal giro accounts play a special role in payment transactions.

In Switzerland, since January 1, 2006, the banks switched to the IBAN format with 21 digits. During the transition period, the old account numbers were still accepted - since January 1, 2010, the beneficiary's IBAN has been mandatory. Banks are therefore allowed to reject transfers without an IBAN, but many banks do not use it. In the case of domestic transfers, the routing is carried out using the BC number that is coded in the IBAN. For online transfers, it is common practice to automatically fill in the field with the BC number when entering the IBAN.

Belgium

Belgian account numbers have twelve digits and consist of three blocks (e.g. 091-0122401-16).

• Three-digit block: Protocol number that provides information about the bank.
• Seven-digit block: Actual account number
• Two-digit block: check digit

The check digit is the remainder from dividing the first two blocks by 97 (mod 97). If the remainder is 0, the check digit is 97. If the check digit is less than ten, a 0 is placed in front.

France

French account numbers are eleven digits long and can contain letters. On checks and account statements, they are usually given together with a code for the bank (code banque = 5 digits), the counter code (code guichet = 5 digits), then the actual account number (Numéro de compte = 11 digits) and a checksum ( Clé RIB = 2 digits) as a 23-digit RIB (“relevé d'identité bancaire”). The checksum at the end of the RIB can be calculated using the standardized algorithm (mod 97).

Spain

In Spain , the account number ( Código cuenta cliente ) not only identifies the account itself, but also contains the identification data of the bank holding the account, comparable to the German bank code . Their structure is uniform across Spain. Spanish account numbers consist only of digits and are 20 digits long, and are divided into 4 sections: First a group of four that describes the bank, then another group of four to identify the branch, then 2 check digits and finally the actual 10-digit account number . The first check digit checks the first 8 digits, the second the last 10 digits.

Spanish account numbers are formatted as follows: 2100 0418 45 0200051332

In contrast to Germany, the check digit calculation method is uniform across the country and uses a weighted Modulus 11 check algorithm .

Calculation example for check digit 1:

 1. ggf. führende Nullen ergänzen: 0, 0, 2, 1, 0, 0, 0, 4, 1, 8
    Gewichtungstabelle:            1, 2, 4, 8, 5,10, 9, 7, 3, 6
 2. Gewichtet aufsummieren:        0, 0, 8, 8, 0, 0, 0,28, 3,48 = 95 = 1*0+2*0+4*2+8*1+5*0+10*0+9*0+7*4+3*1+6*8 = 8+8+28+3+48
 3. Rest Modulus 11 bestimmen: 95 % 11 = 7
 4. Ergebnis von 11 subtrahieren: 11-7 = 4
 5. Falls Ergebnis gleich 10, setze Ergebnis auf 1 bzw. falls Ergebnis gleich 11, setze Ergebnis auf 0.
 Gesamtergebnis: 4

The second check digit is calculated according to the same scheme.

Web links

Wiktionary: Account number  - explanations of meanings, word origins, synonyms, translations

• Description of the check digit calculation methods at the Deutsche Bundesbank (updated quarterly)
• Check account number for check digit calculation for German IBAN (with test data)
• Free PHP library for check digit calculation for German account numbers (with test data)
• further free library C library with ports for PHP and Perl, including bank search according to various criteria
• IBAN check digit calculation (PDF; 75 kB)
• SEPA Account Converter Windows program for converting old to SEPA account numbers

Individual evidence

1. ↑ Deutsche Bundesbank: Check digit calculation methods for checking account numbers for correctness (as of September 2015, [1] PDF).
2. ↑ ^{a b c} European Committee for Banking Standards: TR201 - Register of European Account Numbers ( cnb.cz ( Memento of June 4, 2008 in the Internet Archive ))
3. ↑ IBAN number: Not yet mandatory. November 29, 2009.
4. ↑ bankzweiplus.ch (PDF) “For domestic bank payments, the IBAN or account number must be entered. If you use the IBAN, the BC number will be entered automatically as it is contained in the IBAN. "