The Green Party is taking the capital gains tax (CGT) to the next level with co-leader Marama Davidson now open to including the family home.

She has some big ideas for spending and borrowing too that are not just out of step with her Government coalition partners, but also her own party.

Ms Davidson has stacked up a case to tax the "wealthy elite". She told Newshub the "gap between those struggling and those creaming it is unacceptable".

However, she doesn't seem to know who they are or how much they own.

"Well, a man who owns hundreds of homes, I can't even remember the number. It was such a ridiculous amount of homes to own for one person - there is no need for that," she said, when asked who the 'wealthy elite' is.

Regardless, she says they own too much and that's why the Greens will push hard for a CGT, with Ms Davidson going beyond party policy to even consider taxing the family home.

"I'm open to that debate, to be quite honest," she told Newshub.

But not in any Government led by Prime Minister Jacinda Ardern.

"There will never be consensus on that issue because we ruled it out right from the beginning," she said during her Monday press conference, when asked to respond to Ms Davidson's comments.

Ms Davidson says the proceeds of a CGT will help tackle homelessness.

"It is part of regulating our housing market and that has led to the homelessness situation - the worst we've ever seen today," she said.

But property commentator Ashley Church says a CGT will "absolutely not" help homelessness, telling Newshub the issues are "primarily related to drug abuse and to mental health".

The three governing coalition parties are split on a CGT.

Labour's original policy was a broad-based CGT with an exception for the family home. New Zealand First has historically completely opposed capital gains taxes, while the Greens, at totally the other end of the spectrum, have opened the door to extending the CGT to include the family home.

National Party leader Simon Bridges told Newshub the Greens "don't understand the economy" or issues like "how you build a lot of houses".

Ms Davidson said she also wants to see the budget responsibility rules scrapped - the fiscal straitjacket Labour and the Greens signed up to in opposition that prevent borrowing more.

Ms Davidson now says they're arbitrary - a different take than the Prime Minister who said on Monday: "I would not consider them arbitrary."

Newshub.