At least 1,500 teachers and support staff are set to be made redundant by September as part of the toughest education budget Northern Ireland has ever faced.
The news comes as the Irish National Teachers' Organisation (INTO) union announced that its members will strike next Friday, following a 79% vote in favour of taking action.
Education Minister John O'Dowd revealed that despite receiving an additional £64m from the Department of Finance last month, his resource budget for 2015/16 was still being cut by almost £97m.
One of the most visible cuts will be in staff numbers, due to a £28m cut in the aggregated schools budget.
Last December it was expected that 1,000 teachers and 1,500 support staff may have to be made redundant.
But yesterday Mr O'Dowd estimated that around 500 teachers and 1,000 support staff will be lost.
However, he said the decision to cut staff will rest with schools and the Education Authority, and the full numbers of staff that will be cut will not be known until June.
Schools received letters about the budget last week.
Gerry Murphy, Northern Secretary of the INTO, said: "John O'Dowd has told the education committee schools will likely see 500 job losses for teachers and 1,000 for non-teaching staff due to £28m cuts to his budget. Our members are saying 'enough is enough'."
Chris Keates, General Secretary of the NASUWT, the largest teachers' union in Northern Ireland, said the job cuts announced by the minister would result in a "colossal loss of talent, experience and skill from our schools".
"The scale of proposed redundancies will leave schools struggling to deliver the same level of education with far fewer teachers and support staff," he said.
Ulster Teachers Union leader Avril Hall Callaghan said schools were already pared to the bone from years of cuts.
"Even more modest cuts than predicted are going to have a huge impact on the education of pupils," she said.
Mr O'Dowd told Stormont's education committee he has had to make difficult decisions - and make cuts that he did not want to make.
"This has been the most difficult budget I have had to prepare in my tenure. We are in a financial situation created by others.
"I believe the Executive continues to mitigate against the worst aspects of austerity," the minister added.
Last year the Department of Education had been asked to find a total of £198m of savings from its resource and capital budgets for 2015/16.
In December a department official warned that at least 2,500 teachers and support staff would have to be laid off as part of the effort to meet these budget pressures.
However, in January the department received an extra £64.9m from Finance Minister Simon Hamilton, softening the budget blow.