Green Party co-leader Russel Norman says green economics can provide a solid future for New Zealand without having to sell off state assets.
Dr Norman gave his state of the planet speech in Auckland on Sunday afternoon.
He says the Government is bereft of economic vision and is making a mess of budget management.
Dr Norman says New Zealand's economic shift requires an overhaul of the tax system.
"A capital gains tax, excluding the family home, will move capital away from property speculation," he says. "It will put downward pressure on property prices making home ownership a reality for more kiwis".
Dr Norman says that according to the Tax Working Group, such a tax would boost the Government's finances by about about $4 billion a year.
He says the Greens are also very supportive of the Labour Party's proposal to close some tax loopholes on investment properties.
Dr Norman says price signals and regulations are also needed to protect the country's environment - rewarding businesses who have a good environmental record.
He labelled National's plan to look at partial share sales of four state-owned companies as "bludging off our grandkids".