Ardern confirmed the Green Party would be the first she would have a conversation with in the event Labour needed to form a coalition.

"We have a memorandum of understanding with the Greens, so the first conversation will be with them."

She said Labour's coalition talks would be with those parties it shared values with - and those who the public deliver.

Her vision of Labour's position in a coalition government would be one were it had the balance of power.

"One where we are in a dominant position and where we have real strength and where we can determine direction in government.

"No one wants to be in a position where they are held to ransom."

Ardern was also asked about NZ First leader Winston Peters' comments to the NZ Heraldthis morning that he would not talk to Labour about a coalition unless Labour set out what it planned for taxes such as capital gains tax.

Ardern said Labour had not yet had any discussions with Peters and that would wait until after the election.

"We've shared exactly what our intent is with the public and with Winston."

She denied a capital gains tax was inevitable once the Tax Working Group she intended to form had reported back.

But she said if something had the potential to make it easier to buy a first home it was incumbent on her to do that.

"But I'm not predetermining that this is the best way to address this issue.

"This is a question of fairness and doing everything we can to resolve the housing crisis.

"Whatever we do it will not affect the family home or the land under the family home."

Ardern said English had listed land tax, wealth tax and inheritance tax as if all would be introduced.

"He's wrong and you're wrong."

Reports from overseas, in places such as Sydney, that a capital gains tax had pushed up house prices was one of the reasons Labour wanted experts to take another look at it. It had been campaigning on a CGT in 2011 and 2014.

Ardern said she would not rule out including somebody like former finance minister Sir Michael Cullen on the Tax Working Group but would take expert advice on who was best to lead it.

Asked about family homes held by trusts, she said she had a clear expectation that any tax should not touch a family home regardless of its ownership structure.

Ardern also stuck by the need to ban foreign buyers of property - something she has said Labour would implement by Christmas.

She said the current data on foreign buyers, which showed only about three per cent of properties were selling to offshore owners, was incomplete but there were signs it was having some impact.

"If it's playing any role, it should be stamped out because we can't afford anything that contributes to the overheated housing market."

Ardern also denied hanging farmers out to dry through policies such as water charges and bringing farmers into the Emissions Trading Scheme.

She said Labour would protect farmers from the full cost of its emissions - they would only have to account for 10 per cent initially - and would invest in technology to reduce emissions.

However, she said New Zealand's environmental brand was too important to put at risk.

Asked if other taxes would be reduced to mitigate the costs of any new taxes on households, Ardern said Labour was looking at policies such as tax breaks for those who invested in small start-up companies - similar to the UK's Seed Enterprise Investment scheme.

On her pledge to retire rather than raise the age of superannuation, Ardern said the real neglect was National's refusal to continue contributions to the Super Fund throughout its nine years in office.

She conceded Labour would have to borrow more in the short term to pay to re-start contributions to the Super Fund, but said you could borrow at three per cent and invest at 10 per cent. "It makes good sense."

She ruled out any means-testing on super.

Ardern was also questioned on the rationale behind free tertiary education.

She said it was about preparing Kiwis for the future where technology was leading to greater automation in the work force

"This in our view, if we want to be a more productive economy is where we need to go."

She denied it was an election bribe.

"If it was a bribe it would affect students who are there now and it doesn't."

The Labour Party leader would not be drawn on the costings of the minor parties that could be potential coalition partners.

"First of all I am not going to be held to account on costings for minor parties," she said.

Even if they went into government together Jacinda said it "doesn't meant the government of the day takes them [the costs] on board".

"What we have costed for ourselves is $14.5b and it's there for all to see in our fiscal plan."

She said this included details on where Labour planned to draw its money from and where it planned to spend it.

Ardern has once again categorically ruled Winston Peters being given a shot at the Prime Minister's position in any coalition deal.

"When they [the public] vote for me, the expectation is I'll be Prime Minister, I will not negotiate that."