Banks do not use the same Core Banking Software perpetually. From time to time there may be a need for the bank to move from one CBS to another. During such change in CBS, it has to be ensured that data is migrated accurately from one system to another. RBI and NABARD require banks to conduct external Data Migration Audit after each such migration, by qualified auditors.
We have conducted Data Migration Audits of 40+ banks in India (a total of 750+ branches).