Permanent TSB has outlined plans to cut between 250 to 350 jobs.
The redundancies will be voluntary. It also understood some people could be offered redeployment.
Meanwhile, the bank is to announce an increase of one percentage point in its standard variable mortgage rate tomorrow.
Senior management were briefed on the cost-cutting proposals this afternoon and staff will be told full details in the coming days. The bank is owned by Irish Life & Permanent.
Chief executive David Guinane said the bank was loss-making and that banks which continued to be make losses had to resort to aid from the taxpayer. In order to avoid that outcome, he said, PTSB had decided to increase interest rates.
Mr Guinane said he understood why customers would be angry but he was left with no choice.
Permanent TSB currently employs 1,800 people and has 100 branches around the country.
It has hired consultants Accenture to examine its costs. Its latest results showed that it lost €131m in the first half of last year.
Permanent TSB has been the country's biggest mortgage lender. Now it is affected by a significant decline in revenue since the property bust.
The UNITE trade union confirmed that it has held talks with senior management at Permanent TSB over future restructuring.
'Until we have an opportunity to communicate and consult with our members it would not be fair to them to comment on today's speculation about the company,' said regional co-ordinator Walter Cullen. 'We hope to be in a position to issue a more comprehensive statement to the media on Friday morning,' he added.
On the plans for a percentage point hike in its standard variable mortgage rate, Permanent TSB said larger mortgages tend to be on cheaper tracker mortgage rates. The development is unconnected with the European Central Bank's meeting.
