The Housing Executive has said 450 jobs will go over the next three years in a bid to save money.
A protest is to be held outside a meeting of the Housing Executive
It confirmed the cuts in response to Nipsa claims that 60 temporary staff have been dismissed in recent weeks. The union is threatening strike action.
In a statement, the Housing Executive said: "Most of those who have left were on 13-week contracts.
"The executive is expected to make reductions in our staffing budget but has consulted with Nipsa over this."
The trade union said industrial action could follow as no arrangement has been made to cover the work.
A protest is to be held outside a meeting of the Housing Executive's management in Belfast on Wednesday.
The Housing Executive said the cuts were necessary because of reductions in its staffing budget.
Maureen Taggart, head of personnel for the Housing Executive, said the staff cuts would be primarily administrative and professional/technical staff.
She said the job cuts would also hit management and supervisory levels.
"It is always difficult when staff are released, but the Housing Executive in line with all government departments is required to deliver a 5% effieciency savings each year for the next three years," she said.
"Clearly, we have to plan to protect those staff who are permanently with us and have been with us for some time."
She added: "We have been working very closely with Nipsa on some major reviews which will deliver efficiencies and which we are both commited to looking at and working together on."
However, Bumper Graham from the union said that was not the case and his members were considering how to respond to what they consider "a devastating blow".
"The figures, when you add them up, account to 15% of the Housing Executive workforce," he said.
"This is at a time when the minister has confirmed that we are in our deepest housing crisis for 40 years.
"Our members provide essential services. They deal with the homeless, they deal with housing applications, repairs to tenants' houses.
"It is hard to see how we can move forward on the housing front at the same time that 15% of the workforce is going to be slashed."