Up to 16,000 Ulster Bank mortgage customers are in line to receive payments following recalculation errors by the bank.
The errors related to customers who were in financial difficulty and were engaged with the bank's arrear’s support unit.
When the borrowers exited a period of forbearance, the bank miscalculated what their repayments should change to, leaving them underpaying.
This meant that the amounts that the customers owed did not fall as fast they should have done.
The result was that more interest was paid than should have been.
In total, the bank says 16,000 customers were affected.
It is writing to them to inform them of the errors and to make a payment to offset the underfunding.
"For the vast majority of impacted customers this is a historic issue, and their monthly repayment amount has since been recalculated and is now correct," it said.
"To put this right for customers, Ulster Bank is making a payment to live impacted customers to cover the underfunded amount as well as any additional interest incurred."
"A compensation payment and any additional interest incurred will be made to customers who have since redeemed their mortgage."
The bank has apologised for the blunders which it said came to light when it was reviewing customer repayments on mortgages.
Most of the impacted have now received remediation through the process, which began in March.
The average amount of remediation is €350, with over 80% of customers impacted set to get €400 or less.
5,000 of the borrowers will receive €5 or less or will have suffered no financial loss.
Among the customers affected are some who have paid off their mortgages, moved to other banks as part of the Ulster Bank’s exit, or were previously sold to investment funds.
A small number of existing customers are impacted.
The development, first reported by the Irish Independent, comes in the wake of series of errors at banks becoming public in recent weeks.
