Using data which is out of date can cause inconvenience to customers - their payment might be delayed or not processed - and it places a cost burden on businesses, individuals and banks as they rectify the problems which can arise. In particular cases where 00 is a valid check digit, 97 will not be a valid check digit, likewise if 01 is a valid check digit, 98 will not be a valid check digit, similarly with 02 and 99.
IBAN imposes a flexible but regular format sufficient for account identification and contains validation information to avoid errors of transcription.