Nearly $17.5 million was spent in the overhaul and rebranding of Child Youth and Family Services when it became Ministry for Vulnerable Children this year.
The "obscenely large amount of money" could have gone to reducing child poverty, Mangere Budgeting Services CEO Darryl Evans said.
"I look at that type of money and I think, you know, God, you could feed every kid in the country, essentially."
The total cost for the government department's restructure and controversial name change to Ministry for Vulnerable Children, Oranga Tamariki is $17,431,670 according to figures released under the Official Information Act (OIA).
The Herald is waiting for clarification on whether this figure is GST exclusive.
Of that number, more than $5m was spent on consultants hired to work on setting up Oranga Tamariki, $2.5m on contractors, and $2.8m on changes to IT systems.
The cost of rebranding was about $46,778, while staff in the children's worker roles who had to be rehired were put through $56,000 worth of more intensive background checks and vetting.
The figures come as new Minister for Children Tracey Martin announced last week that the department's name would change yet again - with the "vulnerable" set to be dropped from the ministry's official name. There have been no indications as to how much the latest name change will cost.
Evans said it was easy for the public or a layman to say the CYFs overhaul could have been done more cheaply, but $17m sounded like a "massive" amount of money to him.
"If I think what else could have been done with that . . . it just sounds like an obscenely large amount of money.
"When you're talking $17 million it just sounds incredible, it's massive. It could have gone to a whole range of things, [like] reducing the number of children living in poverty."
Families were coming into his service on a daily basis needing food parcels, Evans said, and he saw many children who didn't go to school because there was no food to pack in their lunchboxes.
According to the OIA documents, the majority of the cost went towards the overhaul of the department, rather than the actual name change.
The "whole of sector shift" involved working with other agencies and the wider community to design new models and establish a better service.
"These streams of work have all been occurring while the vital core work of support and caring for children continued both before and after Oranga Tamariki's establishment," director Nadine Kilmister said in the OIA response.
The amount of activity in such a short timeframe had made the programme "exceptionally complex".
"It has required major changes in culture and ways of working, as well as the development of new investment, operating and practice models."
People with "specialist expertise" from both the private and public sectors were needed to work on the transition.
"Throughout the process, the ministry has also had to balance resourcing for this transformation while continuing to provide existing services . . . core agency staff could not all be taken 'off-line' to work on the system change, so the programme used existing staff, secondees, and external agencies and consultants."
The consultants worked on "fundamental" parts of the change, including the operating model of the new ministry, implementation of legislative changes, and ensuring all 3000 Oranga Tamariki staff working directly with children were "safe to do so".
Establishing the new ministry was a "significant task", Kilmister said, but was only the start of a four or five year transformation.
Where did the money go?
Staff vetting: $56,000
External advice from other Government departments: $125,000
Salaries for fixed term and internal secondees: $5,553,407
External secondees: $969,847
Rebranding: $46,778 (including $6738 for new signage)
IT systems changes: $2,850,700