There are concerns young people seeking mental health support are slipping through gaps in the data if their referrals are declined when they reach out for help.

MP Ingrid Leary, Labour's spokesperson for mental health, welcomed the news last month from Mental Health Minister Matt Doocey, who announced the government would begin publicly reporting youth mental health wait times.

But Leary said failing to count the number of declined referrals meant only half the picture was being told.

This is a problem felt all around the health sector - a report by the Association of Salaried Medical Specialists (ASMS) found one in five specialist referrals (separate to mental health) were declined last year across several districts, but said the extent of the problem nationally was not known because Health NZ did not collate the information.

Leary said to really understand if young people were getting the help they needed, both wait times and the declined referrals needed to be counted.

"And we need to understand where the young people live, which areas of the postcode lottery so that we can better target the interventions," she said.

The Mental Health and Wellbeing Commission agreed counting declined referrals was important.

"The data referenced by Minister Doocey suggests some young people are struggling to find an appointment, do not know where to get help, or feel too embarrassed to seek it.

"Those are important issues, but we also know there are system-level barriers after young people do reach out, including increased declined referrals, unclear pathways, or services not having capacity to provide the right support at the right time.

"Young people have told us they often do ask for help and the NZ Health Survey shows that younger adults (15-34) more likely to seek help for mental health. The challenge is not only whether they know where to go, but whether the system is able to respond effectively when they reach out."

Doocey said it was his expectation - and he had been assured it was best practice - that if a person was assessed as not requiring specialist services they were not just turned away, but referred elsewhere for support.

"What normally happens is they are either directly referred to another service, or back to their GP with suitable recommendations for support," he said.

No young person should be left in limbo, he said, "and anything falling short of that would not meet my expectations".

He said it was "rich" for Leary to comment, as this was the first government to publicly report wait times against targets.

Reporting on wait times would begin from next quarter, and on Thursday, the government would be releasing its Mental Health Strategy at Parliament.

Mental Health and Wellbeing Commission chief executive Karen Orsborn said they too were hearing young people were being declined or meeting other challenges accessing help.

"It's not a consistent picture across the country," she said. "We do have different levels and types of services in some parts of the country compared to others."