Child poverty advocates have launched a new campaign to raise the age of state care from 17 to 21.
The initiative called We Don't Stop Caring, was started by Lifewise, Dingwall Trust, Youthline, Child Poverty Action Group, Wesley Community Action, Christchurch Methodist Mission and Action Station.
The group said it aimed to raise the age so every young person in the country had the right to support and a home-base.
Child Poverty Action Group spokesperson Associate Professor Michael O'Brien said under the current law, children lost the protection of Child Youth and Family when they turned 17, but did not get adult support like student allowances until they were 18.
"It is unrealistic to expect 17-year-olds to exit the foster care system and become completely independent," he said.
"Transitioning to life as an independent adult is difficult, and it only gets harder when a young person already has a disrupted life... raising the age for support would give young people the right to support and a stable home through this important stage of their lives."
Mr O'Brien said leaving care while trying to finish the last years of school was immensely difficult without support.
"The Government is currently reviewing Child Youth and Family Services, including whether the age of foster care should be reviewed... this is the ideal opportunity to fix a flawed policy and make a real difference for our most vulnerable youth."
Fostering Kids New Zealand chief executive Linda Surtees said people had been pushing to raise the age limits for state care for a long time.
She said children should be able to stay in the system until they were 23, because now they left care before they could sign most contracts.
Social Development Minister Anne Tolley said the cut-off age for state care was being considered.
She said the age was something that needed to be looked at, and it had been investigated since April by a panel planning the operational overhaul of Child Youth and Family.
Ms Tolley said the panel would report back with a business case by the end of the year.