A Treasury Report puts the Green's Wealth Tax in Doubt

On July 23, the NZ Herald reported that Treasury advice cast doubt on the Greens' proposed Wealth Tax, however the story was paywalled, limiting the public's ability to verify the details. Within hours, the Taxpayers' Union (spokeswoman Ella Dickson) issued its own release calling the policy an "uncosted socialist fantasy" and claiming Treasury warned a 2.5% wealth tax would "drive significantly more wealth offshore than the Greens have allowed for".

The National Party then backed the same claim. "If you impose a wealth tax, you're kicking wealth out the door," Willis said.

The Treasury advice being cited actually dates to a 2023 request from then-Finance Minister Grant Robertson about a potential wealth tax option. It states it needs information Robertson didn't have but the Greens do, such as the wealth threshold at which the tax begins, and separately states a need for both a Capital Gains Tax and an Inheritance Tax alongside any wealth tax. A former IRD chief economist who co-authored the report suggested a roughly 38% behavioural (avoidance) response, higher than the Greens' own 28% modelling assumption. This is a discrepancy the Greens said reflected too conservative a reading of Treasury's own analysis, accusing Treasury itself of "politicisation."