The EBS Building Society is set to shed a further 200 jobs, according to the Unite trade union.
AIB, which now owns EBS, insisted that the 200 job losses announced today are part of the 2,500 redundancies announced last year and are not new reductions.
A spokesperson said that the voluntary redundancy scheme was being opened up to EBS staff from today and that they have until 11 February to apply.
In a statement it said the voluntary severance scheme has been ongoing since the announcement and rolled out on a phased basis, according to business needs and capacity.
It noted that as part of this phased programme across the group, some EBS staff were now "in scope" to apply for voluntary severance.
At its peak EBS employed 800 staff, but the 200 job losses announced today will reduce its workforce to 400.
EBS was merged with AIB in 2010 as part of the restructuring of the Irish banking sector in the wake of the banking crisis.
The UNITE trade union has condemned the loss of 200 jobs at EBS Building Society as "ripping the heart out of what was once an institution of the people."
Unite official Colm Quinlan described the move as "ripping the heart out of what was once an institution of the people."
He accused EBS of treating workers with callous disregard that would be shocking in a private company, but was unforgivable in a company controlled by the Government.
Unite members will meet on Tuesday 5 February to discuss whether to take industrial action over the cuts.
The union said that as EBS is now fully owned by AIB, an extension of industrial action to the parent bank could be on the cards.