The number of children living in poor households had been decreasing since 2015, but rose in the year to June 2018, latest figures from Statistics NZ show.
About 254,000 children were in low-income homes after housing costs were deducted, up 2.4 per cent from the previous year.
While fewer - 183,000 children - lived in low-income homes before housing costs were deducted, this was a 17.3 per cent jump on the previous year.
About 148,000 children were living in material hardship.
These three figures, released today by Statistics NZ, are the Government's main child poverty measures and will be the baseline rates for current and future governments to assess ongoing progress.
There are six additional measures, four of which showed an increase in child poverty in the year to June 2018, compared to the previous year.
Minister for Children Tracey Martin said the child poverty rates were too high.
"We are committed to halving them ... Today's figures from Stats NZ are part of that process. We can now finalise our child poverty reduction targets and get on with meeting them."
The Government passed its child poverty reduction legislation at the end of last year with cross-party support, except for Act.
The passing of the law was a key focus of Prime Minister Jacinda Ardern, who acknowledged the support of the National Party at the bill's third reading and said reducing child poverty was now "Parliament's collective challenge".
The legislation requires governments to have transparent reporting on poverty levels, a comprehensive strategy on the wellbeing of all children up to 18, and accountability by setting targets for three and 10 years.
The four main measures for the year ending June 2018:
• Low income before housing costs (below 50 per cent of median income, moving line) - 16.5 per cent of children, or 183,000 children
• Low income after housing costs (50 per cent median, fixed line) - 23 per cent of children, or 254,000 children
• Material hardship (missing out on items that could be expected in a typical household) - 13.3 per cent or 148,000 children
• A persistence measure that will look at the length of time in poverty, to be reported from July 2025
The numbers for material hardship include a large sample error, Stats NZ household statistics senior manager Jason Attewell said.
The six additional measures for the year ending June 2018:
• Low income before-housing-costs (60 per cent of median, moving line) - 281,000 children, up 15.6 per cent from the previous year
• Low income after-housing-costs (60 per cent of median, moving line) - 341,000 children, up 8.6 per cent from the previous year
• Low income after-housing-costs (50 per cent of median, moving line) - 254,000 children up 7.6 per cent from the previous year
• Low income after-housing-costs (40 per cent of median, moving line) - 174,000 children, down 2 per cent from the previous year
• Severe material hardship - 65,000, down 12 per cent from the previous year
• Both low income and material hardship (using 60 per cent AHC moving line and the material hardship measure from the primary list) - 98,000, up 14 per cent from the previous year
"Together the nine measures reported in today's release provide a comprehensive picture of child poverty in New Zealand that one measure alone cannot provide," Attewell said.
Martin said the Government will have an initial picture of the impact of its policies - including the Families Package - on child poverty by early next year.
Statistics NZ has also increased the sample size from between 3000 and 5500 to 20,000 households to ensure more robust results from next year. This would allow Stats NZ to publish estimates at a regional level and by ethnicity.
"In the meantime, we used additional data sources and methodologies to produce estimates for the year ended June 2018 that are as robust as possible," Attewell said.
The Government's three-year targets for the main measures are:
The three-year targets are:
• 70,000 fewer children living in low-income households before housing costs are included (a 6 per cent drop)
• 40,000 fewer children in low-income households after housing costs are included (a 4 per cent drop)
• 30,000 fewer children living in material hardship (without basics, healthy food etc) (a 3 per cent drop)