Expat Kiwis and jetsetting workers face higher taxes under a crackdown on residency rules.
Inland Revenue wants to block a loophole that allows "fly-in fly-out" workers to avoid paying income tax.
Migrants buying homes in New Zealand could also be considered tax residents under the proposals.
At present, residents are taxed if they live in New Zealand for six months of the year, or have a permanent place of abode.
Under the changes, factors such as bank accounts and family ties will be given greater weight when determining whether an individual has a permanent place of abode.
University of Auckland professor Craig Elliffe said "significant" numbers would be affected.
"It seems (the IRD) are intending to be pretty tough on this. The desire to collect tax is pretty extreme at the moment."
He also believed migrants who had remained "outside the system" will be in the taxman's sights.
"They may be recent migrants who might only come and spend a month here or less, but if they have access to the property they will be considered a resident."
Nearly a million New Zealanders live overseas, and the majority maintain strong links to home.
One key change could affect landlords departed from New Zealand, but still considered to have access to the house. They would be taxed as residents, even if the property was rented out. This might mean that long-term expats with rental properties would also pay tax on the income they make overseas.
Murray Sarelius, a tax partner at KPMG, said high earners were aware of the proposed changes.
"I have been in contact with a group of expats in Qatar over the changes. They are ... watching it with concern."
Sarelius said there was uncertainty over whether the taxes would be introduced retrospectively, from today onwards, or only apply to people leaving from today.
Submissions to the proposed changes closed on January 31.
An Inland Revenue spokesman said guidelines would be published for "fly-in fly-out" workers once the new interpretation was finalised.
There were no restrictions on foreign ownership of houses, and some believed that offshore owners, particularly from Asia, were contributing to Auckland's house price boom. Revenue Minister Peter Dunne said the proposed changes brought tax policy into line with more workers moving between countries.
New rule targets rented homes
An individual will be resident in New Zealand if they are physically present for more than 183 days in a 12-month period, or if they have a permanent place of abode here.
The abode test looks at whether the person has an available dwelling in this country, and then looks at other links with New Zealand such as bank accounts and family ties. Assessing whether someone has an abode is very fact specific. But owning a house in New Zealand would not, of itself, be sufficient for a person to be considered resident in New Zealand. Inland Revenue will look at it on a case-by-case basis.