The richest 1 per cent of Kiwis have bagged 28 per cent — $42 billion — of the wealth created in a single year.
Meanwhile, the poorest 1.4 million people (30 per cent of the population), got barely 1 per cent — $1.5b — of all the wealth created in 2017.
Credit Suisse data showed wealth grew by $148b in New Zealand in 2017 to a total $1.597 trillion from $1.449t in 2016.
These figures were released by Oxfam today, ahead of their report Reward Work, Not Wealth to be revealed this afternoon.
The report will discuss how the global economy enables a wealthy elite to keep accumulating vast wealth by avoiding taxes, driving down workers' wages and prices paid to producers, and investing less in their businesses.
The research also showed a mere 10 per cent of New Zealanders own more than half the nation's wealth and the inequality gap had widened significantly in the past year.
The wealthy elite have continued to accumulate their assets while hundreds of millions of people struggle to survive on poverty pay, Oxfam NZ executive director Rachael Le Mesurier said.
"This gap is extreme. It's not reducing, so that's a real concern. Inequality is really bad for democracy.
"People of the poorest population tend not to vote.
"Extreme inequality also fractures our society creating 'us and them', the haves and the have nots. This is not okay. "Fundamentally it's trapping millions of people in poverty globally."
Last year, Oxfam's research revealed two New Zealanders had more wealth than the poorest 30 per cent of the adult population; this statistic remains the same.
Le Mesurier said trickle-down economics — a theory that benefits for the wealthy such as tax cuts trickle down to everyone else — weren't working.
"Kiwis love fairness, not inequality," she said.
"Governments can tackle extreme inequality here and globally by ensuring the wealthy and multinationals pay their fair share of tax by cracking down on tax avoidance — then using that money to make our country and the global economy a fairer place.
"To end the global inequality crisis, we must build an economy for ordinary working people, not the very few rich and powerful."
Le Mesurier believed New Zealand needed to have a national conversation about tax to examine the fairness of the structure. "Labour's Tax Working Group ... is a huge opportunity to ensure our economy reflects the fairness that is innately Kiwi.
"It also offers an opportunity for New Zealand to provide an example to many developing countries in using a fairer tax system to reduce the gap." Oxfam's report includes a list of recommendations, backed up by experts, for both governments and multi-nationals to decrease the wealth gap.
The research forms part of a global report released to coincide with this week's annual meeting of political and business leaders at the World Economic Forum in Davos, Switzerland.
New Zealand Trade Minister David Parker is scheduled to attend the gathering, which focuses on global politics, economics and social issues.
Oxfam's 2018 report is the most recent in a series of reports that have analysed economic inequality and its drivers. Each year the report has included an analysis of wealth inequality which draws on data from the Credit Suisse Global Wealth Databook and the Forbes list of billionaires. This Credit Suisse Databook is produced annually and is widely recognised as providing the best available data on global wealth.