A man who spent 18 years in state care says he is "terrified" by the Budget changes to Child, Youth and Family.
Daryl Brougham, who wrote a book last year about his experiences, said the extra $95 million a year for the new "super-CYF" children's ministry would go mostly to private contractors through competitive tenders.
Some of the worst experiences in his life in care were when children's homes closed down because contractors lost their contracts.
"What I see is that with CYF getting privatised, they all compete for the same funding," he said.
"So Barnardos, Fostering Kids, Dingwall, House of Hope, the Salvation Army, the whole lot of them, all they do is compete for funding. They undercut each other in order to get it.
"I'm terrified to think that we have more money going to agencies to compete against each other. Why don't we see how we can use this money so that we all work together?"
The as-yet unnamed new ministry will have a much wider brief than the existing Child, Youth and Family, with a $1.3 billion annual budget by 2019-20 to buy extra education, health, employment and social services for the families of all "vulnerable" children.
Numbers are uncertain, but an expert panel led by Dame Paula Rebstock said one in five children were known to CYF by age 17.
The ministry will "partner" with iwi and other Maori and non-Maori agencies for much of the prevention and care work.