Automatic letters were responsible for New Zealanders in Australia erroneously being told their public healthcare access was being revoked, Australian authorities say.
Some New Zealanders told RNZ they had received letters from the federal health insurance agency cancelling their cards on the grounds their visa status had changed.
New Zealand citizens are legally entitled to Medicare, whatever their visa status.
The family of a Brisbane teenager who has autism and was due to have an MRI scan received a letter in April saying his Medicare was being cut because his visa status had changed, his mother said.
Nicole Forbes-Hood, 38, said the family was told in January his bid for permanent residency was being turned down on health grounds.
She had to ask the local MP to resolve the situation, after speaking to Medicare and Immigration resulted in the whole family being sent temporary cards - even though both she and her husband have dual citizenship.
Other similar cases were also reported to lobby group Oz Kiwi.
Australia's Department of Human Services said New Zealanders were not having their Medicare cards revoked, and their eligibility for free public healthcare was unchanged.
The concerns appeared to be linked to automatic letters sent out when someone applied for a visa change, telling them to provide documents to confirm their ongoing Medicare eligibility, the department said.
They were given 30 days to do so or have their Medicare cancelled.