Ulster Bank is raising its age limit for free banking from 60 to 66 from May of this year.
The development means those aged between 60 and 66 will lose free banking and be charged €4 per month.
The move will affect 30,000 customers at the bank.
One customer – Bernice O'Riordan of Oranmore, Co Galway – told RTÉ News the development was an "infringement on older people."
She received a letter from the bank this morning. She had moved to Ulster Bank to avail of free banking.
However, the lender has pointed out to customers that if they maintain a balance of €3,000 or more in their accounts they can still avail of free banking.
The bank says it does not charge transaction fees on a range of services, although it does charge the €4 maintenance fee.
A spokesperson for the bank confirmed "Ulster Bank is increasing the age limit of the monthly maintenance fee waiver on current accounts from 60 to 66 years of age from 20 May 2017."
Bank of Ireland and AIB offers free banking to over 66s, while Permanent TSB offers free banking to all customers.