The prime minister says an announcement on charging New Zealanders to stay in managed isolation hotels will be made "very, very shortly".
With just two sitting weeks left in the term, time is running out for the government to make law changes that would be needed to enforce any co-payment scheme.
Jacinda Ardern dismissed suggestions the government was struggling to form consensus on the issue, and said it was not her intention to rely on the Opposition to get any plan over the line.
"It would be wrong to assume that it's simply party discussions that are taking time," she said.
"It's actually quite a complex thing to draft legislation over, to make sure that we're protecting the rights of New Zealanders to return home, but also at the same time to make sure that everyone has given good thought to their decision making around travel in this current environment."
New Zealand First leader Winston Peters said weeks ago he wanted returnees to stump up, and today he described the policy was "an ongoing piece of work".
Greens co-leader James Shaw said his party would not support a regime which charged New Zealanders that were already overseas.
"For the vast majority of people who are stuck overseas, we just think it's unacceptable.
"There is a huge ex-pat community, many of whom are stuck in a situation now where they're trying to get home, where their visas are running out and we don't think that's fair.
"If somebody knows that they're going overseas for a short trip or a business trip, given the cost of this, there is a case to made, but for people who have left before the legislation, with absolutely no idea that this was going to happen to them then that's unfair and it's retrospective," he said.
Ardern wouldn't be drawn on whether the government was considering a blanket scheme, or whether it would only charge certain types of arrivals.
"I've said a number of times the different factors that we've been keeping in mind as we're considering this issue. I do want to make sure that I leave it to an actual announcement before giving you any further detail, but there are a range of options that we've had before us that we've been considering," she said.
"When you're already here in New Zealand and you're making a deliberate decision to go overseas, that's something quite different to someone who is overseas returning to New Zealand.
"And I do think that there is some sympathy for New Zealanders who have lived and worked overseas who find themselves caught up in this pandemic and through no fault of their own are now having to find themselves returning," Ardern said.
National Party leader Judith Collins said it was important the government work with the Opposition, rather than just expect it to automatically support its plans.
"The government needs to show us the legislation, they need to actually start treating this as a cross-party issue. We have in principle agreement, but we need to know the detail and we cannot sign up until we've seen that detail," Collins said.
She said that her party would be looking for a broad charging scheme, but it was important that there be an option for exemptions on compassionate or medical grounds.
"There's not a lot of tolerance out in places like Papakura, in my electorate, for people to take extended overseas holidays and we all get to pay the costs of quarantine."
Finance Minister Grant Robertson was asked whether he was comfortable with the cost of managed isolation.
"It's our most important line of defence, so we have to make sure that we protect the safety of New Zealanders and of the people coming in," he said.
"I've been working closely with Minister Woods around the costs, no matter what we do in terms of charging, there will still be a significant cost to taxpayers, but I think all New Zealanders can see around them in their daily lives the benefit of us keeping our borders tight."