Foreign patients have racked up medical bills of more than a quarter of a million dollars in the Bay.
The single largest debt by a non-resident patient is more than $50,000, figures obtained by the Bay of Plenty Times Weekend reveal.
The Bay of Plenty District Health Board released the figures in response to an Official Information Act request by the Bay Times.
The District Health Board said that as of the end of October, non-resident patients owed $274,220 in unpaid medical bills.
The largest debt by a single person was $52,953.
All the unpaid bills were for illness rather than accidental injury, which is covered by ACC.
When asked for a breakdown of the total, the board said the entire non-resident patient debt was for hospital rather than community services.
The board declined to reveal any information on the person who racked up the biggest debt.
The Bay of Plenty Times had requested the patient's nationality and gender, and the date and nature of treatment, but acting chief executive Pete Chandler said the board would not provide specifics.
"[It] may result in the person being individually identifiable which is an unacceptable breach of patient confidentiality," he said.
He said it was not known how long the person had been in New Zealand.
Tauranga opposition MP Clayton Mitchell slammed the level of debt as unacceptable.
He said non-residents in New Zealand needed to have medical insurance and it was incumbent on the Government to pursue those who failed to pay their bills.
"[They] take up valuable beds that could otherwise be used to look after taxpayers," he said.
"You should be chasing those people for their medical costs."
The New Zealand First MP was in the United States last year when his son suffered a severe asthma attack and the family was forced to call 911.
The boy spent four hours in an American hospital, the bills for the emergency care totalling US$4700 ($6800).
"I tell you right now, you have to pay," Mitchell said. "But we had cover and obviously we paid those bills. We had insurance and we got it sorted."
Health Minister Jonathan Coleman's office declined to comment, saying the issue rested with the District Health Board.
Pete Chandler said the board had "an extensive process of internal recovering and third party debt collection".
Asked to elaborate, he said non-resident patients are asked to pay at the time of treatment if they are able, but those who cannot are invoiced.
Those patients are then sent an invoice on the 20th of the month and payment in full is requested.
Payment plans were arranged upon request, and patients who did not pay were sent three further requests for payment.
"If they do not respond then the debt is sent to our contracted debt collection provider," said Chandler.
"If they still do not pay then court processes are commenced."
Costs of emergency department visits varied depending on the location and complexity of the treatment.
The board was aware of only one incident in the last 10 years in which a person had obtained medical treatment fraudulently through use of a false identity.
The person was prosecuted and appeared in court in 2014, with the board listed as a complainant.
The New Zealand Taxpayers' Union said health boards should be making every effort to recover debts from foreign patients.
"This is particularly so when New Zealand's ACC scheme covers accidents that occur here, even for foreigners, so these debts will almost certainly relate to illness or pre-existing conditions," executive director Jordan Williams said.
Williams said many public health systems around the world required passports to be surrendered at the time of treatment to ensure payment before the patient departed.
"If the Bay of Plenty DHB doesn't have the systems to chase debts offshore, maybe it should be considering those types of measures."
Williams said he had once had his passport bonded when he sought treatment for an illness he contracted in Austria.
"The health care was second-to-none, but the Austrians were very practical about this sort of thing - payment was up front, or I wasn't going far."