Judith Collins dubbed Sunday the 'stop the wealth tax day' - warning Kiwis that a Labour-Greens Government would tax their assets.
But Labour has ruled out adopting the Greens' policy, labelling Collins' claims "the last roll of the misinformation dice".
And another numbers blunder from National - it calculated the wealth tax wrong in a social media graphic.
Judith Collins ran into some technical issues and some messaging issues declaring a new day in the calendar: "Stop the wealth tax day."
The Greens have proposed a wealth tax, which would see a 1 percent tax paid annually on anything over $1 million.
"Why bother to save? Why bother to pay off mortgages? Why bother to do anything? Why bother to try and leave things for your children if in fact someone's going to come after it?" Collins told Newshub.
National is keen to try anything to gain traction in the final week, but its figures were off and it's being accused of misleading the public.
It put up an ad claiming an average retired couple with $1.75 million between their home and retirement savings would be charged $140 a week.
But that's wrong. The wealth tax is on individuals and only kicks in at $2 million for a couple - that average couple wouldn't pay a cent.
A National spokesperson told Newshub there was a mistake in the graphic and it was quickly identified, taken down and corrected and a new correct version is up in its place.
National has gone larger-than-life on the anti-tax campaign. They've taken out some big digital real estate - plastering their 'stop the wealth tax' message across the country on billboards and spreading it on the ground in one of Auckland's wealthiest suburbs at the Takapuna markets.
Labour has time and time again ruled out implementing it. But Collins insists it could happen.
"We've already seen them give in to the Greens before and they'll give in again," Collins told Newshub.
"I consider that the last roll of the misinformation dice," Ardern said. "Any suggestion of picking up other parties' plans is mischievous and wrong."
"It's just another case of using misinformation to frighten old people who don't need any more frightening right now to tell you the truth," added Green Party coleader James Shaw.
Collins insists she's being honest with the voters.
"Absolutely, absolutely and I'm saying this: Labour wants to tax," she told Newshub.
Tax attacks against Labour have worked before - but in the past Labour has left question marks over tax policy.
This election they've said the only new tax they'll introduce is their extra income tax bracket.