Ministry of Education is proposing to cut 565 jobs, including nearly 100 regional and frontline roles directly supporting schools.
RNZ understands 225 roles of the jobs are vacant.
It makes the proposal the biggest single slash to a public service agency so far. Oranga Tamariki has also announced it will reduce its workforce by 9 percent.
The Public Service Association (PSA) said it was a brutal and dark day for public servants and the children and young people they supported.
Assistant secretary Fleur Fitzsimons said the proposal included scrapping 87 jobs in the regions.
"People doing work including supporting children with disabilities, migrant and refugee children, advising schools on accessing speech and language therapy, lifting student achievement and helping ensure schools run smoothly."
*If you have information, including documents, about public sector job losses please contact: jemima.huston@rnz.co.nz
There was also a net reduction of 38 roles supporting students with disabilities and learning support needs.
Fitzsimons said the government promised job cuts would not impact frontline services but "these proposals show that is not true".
The curriculum centre, which provided expertise and resources to teachers on the curriculum, would see 202 staff cut from its team, she said.
"While the government has delayed changes to NCEA levels two and three for two years, it's clear that these roles will be needed again from 2026, so it's woefully short-sighted to be shedding all the experience and expertise now.
"At a time when student achievement is falling, when school attendance is a challenge, where is the plan for education? It doesn't add up."
In response to the PSA, the MOE said the union had "mischaracterised" the agency's proposals as impacting services for children.
Secretary for education Iona Holsted said the proposal had been designed to avoid affecting tamariki.
"To be clear, this is a complex process that has required time, and our proposed changes have been designed to avoid impacts on direct services to children, teachers, and principals/leaders.
"The government has been clear that operational decisions on meeting the required savings targets is the responsibility of each agency. As with all change, the ministry is following a formal change process. Final decisions will not be made until after this process is concluded."
The ministry declined an interview with RNZ and did not answer questions about cuts to specific teams and the effect that would have on learners.
The Ka Ako, Ka Ora/Healthy School Lunches Programme was facing slashes to its staff.
Eight nutrition experts and at least six advisers, including Te Aō Māori adviser and food safety adviser, would be axed.
Associate Education Minister David Seymour has previously confirmed the programme itself was under review and was likely to be cut in the Budget.
In a statement, Minister of Education Erica Stanford said savings made by the job cuts would be put into frontline services.
"This direction as already signalled with our period products in schools programme announcement and continuing to fund a school lunches programme."
The minister acknowledged it was a difficult time for ministry workers and their families and encouraged all staff to take part in the consultation process.
The cuts would not impact the frontline or children, Stanford said.
A further, smaller announcement would be made next week to staff in two remaining groups, she said.
Kiwis expect government to 'cut down the waste' - PM
Prime Minister Christopher Luxon said there would be more investment into both Oranga Tamariki, where 447 jobs will be slashed, and the MOE in the Budget at the end of May, but the cuts were expected.
"Those are decisions ultimately for the CEOs of those agencies," he said.
"New Zealanders expect us to make sure that we cut down the waste, we end the wasteful spending, and actually we prioritise our frontline services, our public services.
"I appreciate some of those roles are vacancies and others will be real job losses - that will be a tough time for those individuals that have been impacted ... you can be confident as we go through the Budget, there'll be an increase in support and resources and funding for Oranga Tamariki and education."
Luxon repeated his previous comments that the government wanted "more medical doctors, not spin doctors", but said that was not a reference to the question he had been asked about the jobs in disability and migrant services.
"I'm not saying that, what I'm saying to you is I'm being very clear with the New Zealand people. And they expect this - let's be clear - there's been a massive amount of bureaucracy that's built up in our system, there has been a huge amount of wasteful spending," he said.
More than 2000 jobs have been cut from the public service so far as ministries try to achieve budget savings of up to 7.5 percent.
Minister for Regulation David Seymour previously indicated that figure could hit 7500.