About 200 whānau who have left emergency housing but are unaccounted for are likely to be sleeping in cars, garages or overcrowded homes, an advocate says.
The government recently celebrated a drop in the number of households living in emergency housing, but did not know where a fifth of them had gone.
Ministry of Social Development figures showed between December and June, there were 32 percent fewer households living in emergency housing - dipping from 3141 to 2133.
Of those, 27 percent moved into social housing, 21 percent shifted into transitional housing, and 28 percent were receiving the accommodation supplement for a private rental.
Where the remaining 20 percent had gone remained a mystery.
The ministry was trying to find out, but there would likely always be households it could not keep track of due to limited information in its systems, and the fact that people were not obliged to disclose where they went, its housing general manager Anne Shaw said.
"For example, there may be more people who went into private rentals that the ministry cannot see because they did not access [the] accommodation supplement," she said.
Community Housing Aotearoa deputy chief executive Chris Glaudel said that was unlikely.
He pointed to a report from ministry officials to ministers, obtained by RNZ, containing advice about changes to emergency housing which kicked in on Monday.
"We know that as at 31 March 2024, 62 percent of people in EH have an SAS [social allocation system] rating of A15+, which indicates that the majority of people in EH would struggle to afford, maintain, or access suitable housing," it said.
SAS ratings indicate housing need. Applicants in Priority A, which ranges from A20 to A9, are considered at risk.
"These are not people who are going to slot into a private rental," Glaudel said - they had serious and persistent barriers to housing.
"I just don't see how they would be anywhere other than in somebody's garage, or in a car, or in another unstable situation, maybe back with an abusive partner, because they feel they have no other alternatives."
He questioned where people would suddenly find the money to live in a private rental if they were not getting the accommodation supplement.
Glaudel said he supported the government's move to get people out of emergency housing, "but it needs to be into long term, stable, affordable housing that meets their needs", he said.
"We wholly support the outcomes-based approach, but we don't see the ability to confirm those outcomes with this current policy direction."
The government's data and insights needed to "vastly improve" so it could understand the impact of the changes it made, he said.