So - is she right? Is this misinformation? Well … not really.
National is probably going a bit far to frame the wealth tax as if it is definitely going to happen, but they are not wrong to raise the spectre of it.
Because it remains a possibility – albeit small – as long as we have contradictory positions from the Labour and Green parties.
Even this morning, we saw it play out again.
Here on Newstalk ZB, Ardern ruled out a wealth tax.
"We've said all along that is not our policy, and nor even if we are in the position where we were having to negotiate with the Greens, would we be part of the negotiations," the prime minister said.
But on another radio station, Green Party co-leader James Shaw was told what Ardern had said and responded like this: "Let's find out after the election."
Asked to elaborate, Shaw pointed to the fact that the government is gathering less tax right now, but spending a lot more.
"I don't think that it is credible in that situation not to have a conversation about both the fairness of the tax system, the distortions within the tax system and the amount of revenue that government needs to raise in order ot be able to get ourselves through this crisis and then to pay back the debt that's associated with that. It's just not credible."
As long as the Greens hold to the position that they will push a wealth tax, it remains a credible attack on a possible left-bloc government.
In reality, as I said, there is only a very small chance of a wealth tax. Labour has now ruled it out so often and so vehemently it would be credibility-destroying for them to u-turn on that.
And if you had to choose which of the parties is more likely to buckle in negotiations, it would surely be the Greens. After all, the lure of power is strong, and there will be plenty of other policy wins to dull the pain.
So no, it's not misinformation from the Nats. It's just politics.
