Twenty-eight jobs will be cut at the Department of Internal Affairs' National Library and the Māori, Strategy and Performance branch, the agency has confirmed.
It comes as more than 400 jobs are also wound up in its water reform teams.
DIA said it is announcing organisational changes in a "staged approach" and so far eight roles are affected at the library and 20 in the Māori branch.
Another 18 roles will be disestablished across the department's legal and communications teams, as well as the enterprise portfolio management office.
The Public Service Union (PSU) said the proposal means six legal roles will be cut and commercial work will be fully outsourced to private law firms.
PSU national secretary Duane Leo said that move will drive up costs for projects that have to pay for external legal advice.
"The government promised to clamp down on contractor spending, so how does this make sense? This is spending more on contractors and consultants, not less,"
He said legal work should be retained in-house to ensure the Internal Affairs Department gets favourable terms in contracts and funding arrangements.
DIA said it was required to make savings of 6.5 percent, and that job losses account for less than half of savings identified.
It said changes in its other branches are to be announced in mid-May.
- Read more: Public service job cuts: What we know so far
The coalition government binned the Three Waters reform and is going to bring in a new plan called Local Water Done Well.
DIA said that as of mid-October, 427 staff were working on the old plan but that number stood at 60 on Thursday - most on fixed term contracts - with the majority to finish up at the end of the month and the last few done in June.
It comes at the end of a big week of cuts with Department of Conservation, the Ministry of Culture and Heritage, and the Commerce Commission, among others, all making announcements.