Taxing the super-rich has been tried overseas and hasn't always worked out, one expert says.
The Greens have set their wealth tax rate at 2.5%, but Treasury modelling suggests it could shrink the taxable wealth base by more than 40%.
The party's own modelling puts the reduction at about 28%.
Dentons tax partner Bruce Bernacchi told Kerre Woodham if introduced, we'd be only one of five countries that have it.
He says in 1990 there were 12 countries in the OECD that had a wealth tax, and there are just four today.
LISTEN ABOVE

Simon Bridges: Children's Christmas Parade Trust Chair on hiring a new float painter
07:28

Kerre Woodham: The political circus of this week
07:09

Liam Dann: NZ Herald Business Editor at Large on Stats NZ phasing in monthly Consumer Price Index reporting
05:16