(21)In order to respect privacy and protect personal data, the minimum data necessary for the carrying out of AML/CFT investigations should be held in centralised automated mechanisms for bank and payment accounts, such as registers or data retrieval systems. It should be possible for Member States to determine which data it is useful and proportionate to gather, taking into account the systems and legal traditions in place to enable the meaningful identification of the beneficial owners. When transposing the provisions relating to those mechanisms, Member States should set out retention periods equivalent to the period for retention of the documentation and information obtained within the application of customer due diligence measures. It should be possible for Member States to extend the retention period on a general basis by law, without requiring case-by-case decisions. The additional retention period should not exceed an additional five years. That period should be without prejudice to national law setting out other data retention requirements allowing case-by-case decisions to facilitate criminal or administrative proceedings. Access to those mechanisms should be on a need-to-know basis.