Ulster Bank is to cut 110 jobs at its Retail Problem Debt Management Unit, affecting staff in Dublin and Belfast.
More than 30 new roles will be created by the bank, however, which will partially offset the cut.
Ulster Bank said the job losses were part of its ongoing cost-cutting programme, details of which were first announced in 2012.
A spokesperson said the bank continued to "implement the agreed changes to our operating model" and had today informed staff in the affected unit of its plans.
However, the Irish Bank Officials' Association has expressed concern about the cuts, saying the unit's staff were involved in sensitive negotiations around mortgage arrears.
It said a similar unit based overseas "may not be as attentive or understanding of the needs of customers".
It called on RBS Group to defer its decision on the arrears unit until the review of the banking group's operations was completed.