Gareth Morgan's Opportunities Party has released its first piece of public policy, promising to change what is taxed, not the amount collected.
The Opportunities Party was launched last month in a bid to push away from establishment and career politicians.
The tax policy, which matches the content of a Morgan Foundation report on tax released in April, proposes deeming a minimum rate of return on all productive assets, including housing and land.
Those who already declare at least that level of income will be unaffected and those who don't will pay more, the party's tax policy statement said.
It estimates about 80 percent of adults will be either unaffected or pay less tax as a result of the suggested reform, with the remaining 20 percent paying more.
"But don't fret, we can afford it," said Mr Morgan. "I will pay considerably more tax, so will John Key."
It would mean people could be taxed for owning the house they live in or even for an expensive car.
Overall, the fledgling party's package would be tax neutral, with every additional tax dollar collected given back via income tax cuts, it said.
Mr Morgan said there's a big pool of untaxed income represented by the benefits derived from the equity people have in their houses and other wealth they've accumulated, yet that wealth produces no or very little taxable income.
It isn't a capital gains tax, he said. "It's much more efficient and fair than that."
The policy suggests stepping up the required minimum taxable earnings rate over a few years so asset owners have time to adjust. That would also allow pensioners who own their homes to pay the tax via a mortgage with the Inland Revenue Department.