Labour leader Jacinda Ardern has come out firing, accusing National of lying and scaremongering over her party's tax plan.
National MPs have been taking aim at Labour's tax proposals, including in daily campaign newsletters.
That includes one sent by deputy leader Paula Bennett yesterday.
"If we stall New Zealand's growth with the seven new taxes Labour wants to introduce - including a capital gains tax, land tax, inheritance tax, regional fuel tax and a punitive water tax on farmers - along with significantly more debt to cover their spending spree there won't be any money to help those who need it or when the country needs it," the newsletter reads.
National has also released a new attack ad on Labour's tax plan.
While Labour has flagged a capital gains and a land tax, excluding the family home and property, it has ruled out any increases to income tax, and leader Jacinda Ardern told RNZ there would be no inheritance tax.
Ms Ardern told a meeting of more than 600 Grey Power members in Nelson it was an election of "two halves".
"I have said I want a working group to look at what we can do to turn around our housing crisis in New Zealand.
"That is not about inheritance tax, it is not about death duties, it is not about scaremongering - it's about making sure everybody has a home."
Labour also released a its calculator to show voters how much they would gain under its Families package.
National produced own calculator in May to show the impact of its Families package.
Ms Ardern said she had responded as quickly as she could to "fake news" throughout the campaign.
"It's always frustrating in an election campaign, and you don't want to waste time responding to claims that are simply factually incorrect, but it's the nature of politics sometimes, we've certainly done our best to push back hard."
RNZ's latest average of polls has National just under 1 point ahead of Labour. The average was updated after last night's Newshub-Reid Research survey put National 10 points ahead.
PM: 'What are Labour's intentions on tax?'
National Party leader Bill English said his party was not carrying out a smear campaign on the Labour Party's tax plans but merely asking the questions the public needed answers to.
"It's getting in at the question New Zealanders are asking. What are Labour's intentions on tax?
"What surprises me is the Labour Party don't seem to think it matters but actually this is about the cash in people's pockets."
Mr English said Labour was spreading uncertainty.
Campaigns plan to catch early voters
As more people take advantage of advance voting, politicians have planned their campaigns accordingly.
This year there are nearly 500 early voting booths around the country - more than ever before - and the Electoral Commission estimates up to 50 percent of the electorate could cast early votes.
Ms Ardern decided to vote early, forgoing the usual election day photo op, and said the start of advance voting marked a different phase of the campaign.
"We wanted to get out all of our major policies early for two reasons, because of early voting but also because we wanted to release our fiscal plan and make sure there was enough time for people to see we had costed all of our agenda."
National leader Bill English said his party had wanted to clearly differentiate itself from Labour.
"We need to put to voters very clearly the choice that they've got, in this case in this election between New Zealand going forward, building on its strength or slowing the economy, reducing incomes."
New Zealand First leader Winston Peters said early voting made no difference to his campaign.
"I suspect a lot of people wait till the last moment until they've heard everything and then they make up their mind - that's why I'm going to campaign till the very last moment."