Labour says the Government has known about Australia's deportation policy since the beginning of the year, and has been planning for an influx.
Prime Minister John Key will face Australian Prime Minister Malcolm Turnbull over the detention and deportation of hundreds of Kiwis when they meet on Friday.
He says the issue will dominate their talks.
Labour's foreign affairs spokesman, David Shearer, says at least six government agencies including police, foreign affairs, health, justice, immigration and internal affairs have known about the deportations since the beginning of the year.
"While John Key has said multiple times he doesn't have details, the Government has been preparing for an influx of more than 1000 New Zealanders who have served time across the ditch," he said.
"The return of these people - many of whom have no jobs, accommodation, friends, family or support systems here - is likely to cost New Zealand millions."
Mr Shearer says the laws took effect in December and the deportations have gone from a handful a month to dozens, with hundreds more in detention.
Forty New Zealanders facing deportation are being held in the Christmas Island immigration detention centre and 200 in Australian detention centres overall, it has been confirmed.
Mr Key says he pushed the issue with former prime minister Tony Abbott, whose government set the policy, and Australian Foreign Minister Julie Bishop.
There's a special relationship between the countries and there should be a "carve out for New Zealand in some form", he told the Paul Henry programme this morning.
"We need to negotiate with these guys - not try and put them in an arm-lock."
Mr Turnbull was a moderate "thoroughly reasonable guy" with a "big brain on him", Mr Key said.
"We will have good conversations with him."
Australian immigration laws mean anyone who isn't a citizen and who has served a sentence of 12 months or more can be sent back to the country of their birth.