Allied Irish Banks has claimed 4% of its mortgage customers have decided not to repay the money.
In an address to the Oireachtas Finance Committee, AIB chief executive David Duffy also claimed that 2,000 customers in arrears have cash deposits big enough to clear their debts.
And on the investment side of its business, Mr Duffy said the bank has found 1,000 accounts where buy-to-let investors had intended to use rental income to pay for their lending but are now using the money for other needs.
Mr Duffy is the first of the country’s top bankers up before the committee to discuss the financial services sector and activities within the four main lenders.
Committee chair Ciaran Lynch said the meetings aim to help find sustainable, long-term solutions to the mortgage crisis and measures to ease the burden on struggling homeowners and distressed borrowers.
Last month, the Central Bank revealed that 98,000 mortgage holders were in arrears by 90 days or more at the end of June.
The Chief Executive of Allied Irish Bank also said the institution has exceeded targets on tackling mortgage arrears set out by the Central Bank.
Mr Duffy said in some cases that does involve debt write-offs.
He also said the bank is more than meeting the demands of the Government and Central Bank.
Mr Duffy said: "We have made 12,500 offers of solutions in addition to our active day-to-day management and 4,400 permanent solutions have been implemented.
"Again, just to remind the chair and the committee, the regulatory targets are for offers, they are not for resolution. Resolution in some cases, the simple cases, can be straightforward, they can be done in a month or two.
"In some cases with multi-debt connections, it can last six to twelve months."
AIB also issued a series of figures on how it has handled the mortgage arrears crisis on its books.
