Politicians on both sides are rejecting suggestions foreigners pay for medical care before getting treatment.
Figures released to Newshub under the Official Information Act show more than $35 million in unpaid debts has been written off in the past three years at three Auckland region district health boards (DHBs).
More than $90 million was invoiced to foreigners needing medical care at facilities operated by Auckland, Waitemata and Counties Manukau DHBs, but up to 40 percent of it wasn't recovered.
"The taxpayer invests an extraordinary amount of money in the public health service," National Party health spokesperson Michael Woodhouse told Newshub.
"It's becoming increasingly strained, and I think their expectation will be that those resources are expended on people who are eligible for publicly funded services, not those who are coming from overseas. There is a sense of squeamishness about asking people for payment details, but the reality is somebody is going to have to pay for the services that are provided."
Accidents are covered under ACC, but not other medical care. Labour MP Peeni Henare told The AM Show the cost of recovery had to be weighed up against what's owed.
"We think about how much foreigners bring into our economy. We must also remember that many of those people that get that treatment are here visiting family members. Are we now suggesting we chase up those families for that bill? I think you'll find a fair amount of families pushing back on that one."
National MP Judith Collins agreed.
"You can't go after people's families who happen to live in New Zealand... that's all going a bit too medieval. I'd hate to see a situation where people were left at the emergency doors waiting for someone to come and swipe a credit card. I'd hate to see that. I don't want to see that in New Zealand."
Henare said New Zealanders are better than that.
"If a visitor comes here and finds themselves ill and in need of treatment, I think we'd be the kind of country that would help them."
Acting Health Minister Julie Anne Genter and the DHBs declined to comment.