Permanent TSB has become the latest Irish bank to introduce negative interest rate on large deposits.
The move, which takes effect from 1 December on the expiry of customers' fixed term deposits, will impact around 200 customers.
Collectively they have around €450m on deposit with the lender, sources have indicated.
However, the bank says it has no plans to introduce negative rates for more than 99% of its customers, including personal customers, small and medium sized businesses or charities.
The bank has written to the impacted customers in recent days to inform them of the decision, but it has not yet indicated what rates will be charged.
However, it is understood that it is likely it will be in line with the wider market where other banks have been charging customers with large deposit balances for holding their money for some time.
This is because the European Central Bank has for some time been charging banks negative rates for holding money, forcing the banks to pass this cost on to customers.
Those being charged the negative rates by Permanent TSB include other financial institutions such as credit unions, insurers, public bodies and large corporates.
"From 1st December 2021 we will begin to introduce negative rates for this small group of corporate customers on expiry of their current Fixed Term Deposit, as it is not appropriate that a personal and small business bank would continue to cover the cost of negative interest rates for other financial institutions, public bodies or large institutions," the bank said.
Permanent TSB is currently teasing out plans with NatWest to buy a large part of the loan book of the departing Ulster Bank.
The deal would be worth around €7.6 billion and would include Ulster Bank's performing non-tracker mortgage book, its performing SME/Business Direct business, the Lombard Asset Finance loan business of Ulster Bank and 25 branch locations in Ulster Bank’s network.