BANK of Ireland wrote off €2.3m in bad mortgage debt in the first half of last year.
The figure was revealed in recently published correspondence submitted to the Oireachtas Finance Committee.
Chief executive Richie Boucher had been accused of giving "minimalist" answers to the committee last November. He said the vast majority of the bank's mortgages were being paid on time.
Unlike Bank of Ireland, AIB would not disclose the amount of its mortgage write-offs, stating it didn't have the figure.
At the end of last September, there were 761,954 private residential Bank of Ireland mortgage accounts for principal dwellings to a value of €111.2bn. Of this, 86,146 were in arrears of more than 90 days.
The Central Bank has warned the banks that they must do more to tackle the mortgage arrears problem.
Independent TD Stephen Donnelly questioned whether the banks would engage with the new personal insolvency legislation.
"I'm not surprised (with the Bank of Ireland figure)," Mr Donnelly said.
"They're not doing it. They've been giving billions of euro to deal with this problem. We've got new legislation which is too weak to force them to deal with it, despite its best intentions and they're not doing it."