New Zealand First leader Winston Peters has accused Labour and the Greens of "naked political self-interest" over the proposed COVID-19 managed isolation charging system, describing it as an "incredibly inequitable regime".
The Government is proposing to only charge New Zealanders who enter the country for up to 90 days, or who leave New Zealand after the regulations come into force, at a cost of $3100 per person in a room.
The Government has set aside a total of $479 million to pay for the costs of the facilities until the end of the year - but the proposed scheme would only bring in up to $9 million, leaving the taxpayer with a huge bill.
Peters said New Zealand First will support the passage of the COVID-19 Public Health Response Amendment Bill, but he has invoked the 'agree to disagree' provision of the coalition agreement with Labour.
He said New Zealand First "cannot support the unfair eligibility criteria for those New Zealanders being asked to contribute to their managed isolation or quarantine costs".
Labour's confidence and supply partner, the Greens, have claimed a victory by ensuring that New Zealanders who were overseas when COVID-19 hit will not be charged for the cost of isolation or quarantine if they return home to live.
Green Party co-leader James Shaw said the Government should be supporting people to come home if that is what is needed for their wellbeing.
"Kiwis overseas are facing job losses, financial insecurity, and not knowing when they'll see their families again. Now is not the time to be making things harder for our people overseas."
Peters disagreed and blasted Labour and the Greens.
"We believe that the Green Party opposition to the originally proposed policy - that all returning New Zealanders be charged - alongside the incredibly inequitable regime proposed by our coalition partner, is putting naked political self-interest ahead of a prudent public policy response," Peters said.
"It is quite clear to New Zealand First that Labour/Green opposition to a more equitable and consistent [managed isolation] charging regime opens them to the allegation that they are being overtly political," he added.
"Why? Again, the Greens and Labour leave themselves open to the perception that they see New Zealanders overseas as a source of votes for the looming general election, so public policy integrity has given way to electoral strategy.
"This is grossly unfair on the New Zealand taxpayer, burdened with the burgeoning cost of maintaining the [managed isolation] system - already estimated to be half a billion dollars for the remainder of the year."
Prime Minister Jacinda Ardern said political parties will take different views.
"Ultimately, this is only the second time that we've seen that 'agree to disagree' provision and we still have a policy that we will be able to roll out which I think is a fair one," Ardern told reporters on Wednesday.
"We're seeing an increasing number of New Zealanders who might seek to go overseas for reasons that are optional, frankly, such as holidaymakers," she added.
"I don't think it's fair that New Zealand taxpayers be the burden of that, so this is a balanced approach that I think brings in fairness to the scheme."
National Party leader Judith Collins described the policy as "a load of nonsense".
"They say they're going to get about $9 million to $10 million back and it's going to cost New Zealanders close to $500 million," she told reporters. "I just think it's the sort of policy you have when you don't actually want to have a policy."
Collins said the Government should be "ashamed" of themselves.
"I find myself agreeing with Winston Peters which is worrying, but there we go," she said. "Winston Peters agrees with us. It's very clear from what he said today... clearly we need to have a more reasonable contribution."
National proposed earlier this month that, from October 3, all returnees should be charged $3000. The current cost is about $4000 per person, which has so far been covered by taxpayers.
The minister in charge of managed isolation, Megan Woods, said there were legal implications to consider under the Bill of Rights Act, which protects Kiwis' right to enter New Zealand unimpeded.
"We have carefully considered how to design a system that is fair and not a barrier for returning New Zealanders. Indicative modelling shows that the scheme will generate between $2.2 million and $8.8 million a year, at a cost of recouping that of $600,000," Dr Woods said in Parliament.
"The Government's proposal has struck an appropriate balance to ensure taxpayers aren't forking out for people who want to come or go for holidays or business, while returning New Zealanders who want to come home to live are able to do so without unreasonable limitations."