A new scheme to charge entrants to New Zealand has been attacked as unworkable and pointless.

The New Zealand government has announced plans to start charging some international arrivals, allowing citizens to return to live for free, but not holiday-makers.

Prime Minister Jacinda Ardern has defended the scheme as "a fair one" even as her deputy Winston Peters called it "dreadful public policy".

An estimated three to ten per cent of arrivals to New Zealand will be asked to pay a fee for their government-mandated isolation designed to keep COVID-19 out of the community.

That fee has been set at $NZ3100 ($A2880) per adult with $NZ950 ($A882) for an adult and $NZ475 ($A441) for a child sharing the same room.

The charges won't come anywhere close to recouping the budgeted $NZ471 million ($A438 million) for the isolation regime.

The government says less than $NZ10 million ($A9.3 million) will be collected through the scheme.

But with an election on September 19, the government was under increasing pressure to recoup some cost or stop abuse.

"I think it's a fair one. It lets Kiwis come home to work to contribute to our economy and it says if you're someone going on a holiday, that's when you pay," Ms Ardern said.

Arrivals and departures for business reasons - including professional athletes - will be expected to pay.

The government will run an exemption process for compassionate reasons.

The scheme will impact Kiwis based in Australia more than any other country; of up to 900,000 Kiwis estimated to be living abroad, two-thirds live in Australia.

The issue was a particularly thorny one for Ms Ardern's government, faced with legal and political hurdles ahead of the September 19 election.

The Bill of Rights grants every NZ citizen the right to enter New Zealand, meaning the government had to design a scheme which was not liable to legal challenge in the courts.

Furthermore, government parties were at odds on the issue; the Greens felt a fee was unfair, while New Zealand First wanted to charge a greater number.

"Severely limiting the number of New Zealanders who will contribute ... is a dreadful public policy response," Mr Peters said.

"This is grossly unfair on the New Zealand taxpayer, burdened with the burgeoning cost of maintaining the system."

Opposition leader Judith Collins said it was "the sort of policy you have when you don't want to have a policy" and "a total failure and they should be ashamed of themselves".

It remains to be seen whether the system will even work.

Overseas-based Kiwis returning to New Zealand for over 90 days will avoid a fee, while those for 89 days or less will have to pay, with Housing Minister Megan Woods saying the government was relying on "a trust system" to know the length of the stay.

Legislation to enact the scheme will be rushed through parliament in the next week to ensure it becomes law before the House rises at the end of the term.

Despite a small number of escapees from isolation facilities, it has been a roaring success - New Zealand has not recorded a locally transmitted COVID-19 case in the community for three months.