You do this when becoming a customer with us, so that the account is pre-registered when you want to make a withdrawal.
Most banks use a 4-digit clearing number followed by the account number. An exception applies to Swedbank accounts where the clearing number starts with the digit 8.
Swedbank
If you have a Swedbank account where the clearing number starts with the digit 8 and the account number has 8 or 9 digits, you need to add one or two zeros at the beginning of the account number so that the total length becomes 15 digits (including the clearing number).
Example: CCCCC 0XXXXXXXXX
C = Clearing number, X = Account digit