The National Party says the situation at the country's District Health Boards is not sustainable and something has to give.
Eight out of the 20 DHBs have yet to sign off their annual spending plans for this year.
The books aren't looking great in Canterbury especially, where the DHB is expecting a $100 million deficit.
National's health spokesman Michael Woodhouse told Kate Hawkesby the public should have an expectation all public entities work within their means.
"The fact that not only Canterbury, but a significant number of the DHBs are now blowing out financially is a serious concern."
"There are certainly ways in which the services can be deployed that are more efficient than the model that we have got," he said.
"The question for the Government is whether or not they are willing to spend a lot of time and effort reforming that."
He said it is still unclear how much worse the budget blowouts could get.
"We don't know how much worse it is going to get because the Minister [David Clark] is not telling us."
"Normally financial data for each month of the year is put up on the Ministry of Health website [but] that hasn't been updated since June last year, so we are really flying blind."
Eight of the 20 DHBs still do not have an approved plan which is a real concern, Woodhouse said.
"We just don't know where they are at...I'm guessing over $0.5 billion by now [but] it could be worse."
He said it's not sustainable and something eventually has to give.