Opposition leader Christopher Luxon is continuing to flag tax cuts and government spending as two of the battleground subjects for the next election.
National is launching a major offensive against the government, promising to reverse every tax increase imposed by this Labour government.
That would include a commitment to scrap the 39 percent top tax threshold for income over $180,000 - eventually - along with other taxes imposed under Labour.
The government however has told National to put up or shut up, claiming there are already major problems with the numbers.
National Party leader Christopher Luxon told Morning Report there were big economic issues that needed to be addressed.
A new Commerce Commission report on the supermarket sector found competition in the industry was not working well for New Zealanders.
The commission recommended that more land be made available for new grocery stores, changes be made to planning laws and the use of restrictive land covenants be banned.
Luxon said he thought the report was on balance heading in the right direction.
"It doesn't get you away from the bigger problem which is that the cost of living crisis and the inflation that we're dealing with is coming from more than just not enough competition in the supermarket sector put it that way."
There were bigger, broader economic issues, he said.
"There's a whole series of reasons. New Zealand's got the second highest inflation in the developed world, just behind the US. We've obviously been spending a tremendous amount of money, we've been relying on low levels of interest rates and frankly we haven't been doing enough to create pro-business microeconomic policy either, we're just relying on government spending and low interest rates."
The Ukraine crisis has also sharpened the screws on cost of living.
He said National definitely would have spent money on Covid relief but there was wasteful spending happening.
"We do think there is wasteful spending" - National Party leader Christopher Luxon
Luxon said it was about the quality of spend, and the three waters reforms, added bureaucrats and the upcoming restructure of healthcare were all areas of wasteful spending.
"I'm not talking about not spending money or making cuts to public services at all but there is some really wasteful spending going on."
Govt dismisses National's fiscal plan
Tax cuts are now a familiar election battleground between National and Labour.
National lost some credibility in the weeks leading up to the last election with its fiscal hole fiasco - the last thing it needs come 2023 is a repeat while trying to present itself as a better economic manager.
The government has dismissed National's latest tax cut plan, with Finance Minister Grant Robertson yesterday saying the maths just did not add up, and would result in cuts to health and education.
"Certainly this is a repeat of the mistakes made by the likes of Paul Goldsmith. The point that I was making was that you can't have all three of the things that they want all at once. You can't be wanting to cut taxes, reduce debt, and either maintain or increase spending."
He said there also appeared to be two versions of National's factsheet - the second one missing a line which said it used a 2019 Treasury model for costings.
"We need them to come up and tell us exactly what costs they had, but we're doing some work on that."
He said Luxon's speech had reeked of opportunism and did not contain the new, positive ideas promised under the new leadership.
"Right now is the wrong time for this policy ... this would be an inflationary policy, it's untargeted, it would simply be pumping money into the economy at a time where it should be focused interventions not these broad-brushed ones.
"It was the same old, tired old ideas that you'd expect unfortunately from the National Party ... certainly the evidence we've seen from the last few goes that the National Party has had is that they just can't make things add up properly and there isn't a level of transparency here that I think we need."
National's finance spokesperson Simon Bridges said scrapping the government's other various taxes would cost about $1.3b a year, but they did not have timeframes, and the cost was still viewed as an estimate.
He said he stood by his numbers.
"I think Grant Robertson's reached peak fiscal hole. There's just a sense with this guy that he's under pressure, he can see this cost of living crisis that the government is in and actually needs to find some relief for New Zealanders ... and so is flailing around trying to make these allegations to muddy the waters.
"They don't stack up. I've been around a while, I've been economic minister, associate finance minister, there is no hole."
He said they got their costings direct from the various government departments, and there was no trick in any of it.
"For example with the 39 percent top tax rate there's Treasury modelling and so on there that does give us the sense that is somewhere around circa $700m, $800m, but probably increasing.
"Tax indexation should happen now and we've fully costed that. We're also clear that in principle whether it's the 39 percent tax rate, whether it's tax deductibility, whether it's the regional fuel tax, whether it's the bright-line extension, they also should go in our first term.
"Chris Luxon has made that commitment. We will be clear on the timeframes and the exact costings in our pre-election fiscal plan, and we'll stand by those numbers in our timeframe then."