Ulster Bank has apologised after a blunder has left thousands of customers facing higher mortgage repayments for the rest of the year.
The bank has admitted it miscalculated the tax relief on 7,500 tracker, variable and fixed-rate mortgages, with customers who underpaid now being asked to make up the difference.
Affected customers will have to pay an average of €16 extra a month until December to make up the shortfall.
The bank says customers have been notified in writing.