AIB is shutting down its Cashsave account, which will impact on about 400,000 customers.
Half of the 400,000 who have a Cashsave account use it for day-to-day banking as the account comes with a Laser card.
Those whose Cashsave accounts have debit or Laser cards, or who have direct debits set up, will now be moved to a current account.
AIB said the move would "simplify and streamline" its account offerings.
It admitted that many of those who used the Cashsave account for everyday banking could now end up paying fees.