Hundreds of workers could leave the Ministry for the Environment as part of cost cutting measures, the Public Service Association says.
The ministry has called for voluntary redundancies.
The PSA said the ministry had been told to slash costs by 7.5 percent.
Members asked for a voluntary redundancy option, knowing cuts were coming, but job cuts were short-sighted, the union said.
It said the government was prioritising tax cuts despite the ministry's "vitally important role".
Ministry deputy secretary of business transformation and services Laura Dixon said "expressions of interest" for voluntary redundancies from permanent staff had been called for on Monday.
Dixon said the government was looking to find $1.5 billion in savings - and like other government departments, the Ministry for the Environment had also been asked to find savings.
"While the impact of the savings exercise on our work programme and jobs won't be clear until after Budget 2024 on 30 May, we know our organisation will need to reduce in size. Staff have been told redundancies are likely.
"The ministry began an operating model review in June 2023 - in part to prepare for a predicted decline in in our baseline over the next few years, as time limited funding for a range of reforms ended. As part of this we reshaped the organisation around our core functions, and identified new ways of working, systems and processes. We also put in recruitment controls, and reduced the size of our tier 2 and 3 leadership cohort by more than 20 percent.
"From today, staff will have the opportunity to submit an expression of interest (EOI) for voluntary redundancy, before a likely formal change proposal and consultation process later this year."
Dixon said staff could submit their interest until midday on 19 April. There was no "specific target" in mind and the leadership team had full discretion over whether it accepted an EOI or not.
"We acknowledge this is a challenging time for our people. Our goal is to keep them informed and supported throughout the upcoming change," Dixon said.
Job cuts at Callaghan Innovation
Meanwhile, about 30 science and engineering jobs at New Zealand's largest research organisation are on the line, as public sector agencies continue to try and meet the government's demands to cut costs.
Callaghan Innovation said it had not been asked to make a specific percentage of savings, but the organisation was looking at a proposed "strategic reset".
Chief executive Stefan Korn said the agency's board had directed a refocus on its original purpose, which was to support industry-led science and technology-based innovation - and its commercialisation.
"The current strategic reset is about aligning more closely to our core functions. In particular the board is determined to focus the organisation on working with the private sector directly to help turn their science, technology and innovation into increased revenues and profits for New Zealand businesses."
This would ensure it could make the biggest impact on the sector while also addressing cost pressures and managing ageing infrastructure, Korn said.
The agency currently employed 382 full time equivalent (FTE) staff, meaning the proposed changes could affect just under 8 percent of its workforce.
"The next phase of the reset will involve consultation with the scientists and engineers in our Innovation Expertise Hapū, where around 30 FTE roles may be affected," Korn said.
"I acknowledge this is a difficult time for many of our scientists and engineers, who are widely respected for their contributions and high-level of expertise in their respective fields."
A final decision was expected in May or June, following the completed consultation process.
