900 jobs are to go at Quinn Insurance offices, with the jobs to go on a voluntary basis.
It is expected the cuts will happen over a 12-15 month period.
The biggest job losses will be in the largest office, Blanchardstown, which currently has a staff of around 800.
Around 301 jobs will go there - 65 in the first phase, which will take place over the next two to three months.
The head office in Cavan will lose around 226 jobs out of 700, with 121 going in the first phase.
In Enniskillen 179 jobs will go, with 87 going in the first phase.
Navan will be particularly badly hit, with around half the workforce going, 109 out of 220. 37 will go in the first phase.
In Manchester, 48 out of the 100 jobs will go.
The redundancy terms to be offered to staff will include four weeks of pay per year of service on top of the usual statutory entitlements.
The redundancies, which will be voluntary, will result in a saving of €30m per year for Quinn Insurance.
Earlier, the Quinn Group said it had 'reluctantly' decided that it should sell its Quinn Insurance business.
Quinn Group said that in view of the funds needed to meet the requirements laid down by the Financial Regulator, the future of Quinn Insurance was probably best protected under new ownership.
'Accordingly we will be working closely with the joint administrators to see if this objective can be achieved in as short a time as possible with the hope that this will protect the maximum number of jobs,' the statement said.
In a personal statement from Sean Quinn, he said he was 'devastated' at the announcement of the impending redundancies.
Joint administrators Paul McCann and Michael McAteer of Grant Thornton said the projected redundancies could be reduced if more customers are won.
'This is a difficult announcement to make and a considerably more difficult announcement for the workers of Quinn Insurance to hear. The scale of what we face is considerable.
'Unfortunately, this process is necessary in order to sustain and grow a viable insurance business.'
They said that they will continue to talk with the Financial Regulator in order to allow profitable business lines in Britain to be reopened. But certain loss-making lines of business will cease, they added.
'The restructuring process has taken into consideration a business plan which, we are confident, is realistic in the context of what it known and expected about conditions in our markets,' the administrators said.
The administrators said Quinn Insurance should be sold as a going concern as its value in its business model, its people and its claim management system.
They said they have received more than 40 expressions of interest from outside parties in buying Quinn Insurance. The contacts were made without being asked for and no discussions on them had yet begun.
Minister for Enterprise, Trade & Innovation Batt O'Keeffe was to meet with the administrators earlier this evening to hear their view of the Quinn Insurance company.
Asked earlier today why he did not meet the administrators before today's announcement, he said that would not have been appropriate.
Minister O'Keeffe described the job cuts announcement as devastating for the workers and their families. He said the Government would do everything in its power to try to get replacement jobs.
He said he is putting an inter-agency group in place comprising Enterprise Ireland, FÁS and others to support workers who will lose their jobs.
Watch an interview with Sean Quinn following the appointment of administrators to Quinn Insurance in recent weeks