Prime Minister Chris Hipkins has derided the National Party's plans for tax receipts as "bumper sticker slogans", and says the party needs to show where they would cut spending.
National's Finance Spokesperson Nicola Willis says their policy is about accountability and delivering better results from taxpayer money.
National announced the move as one of three tax transparency policies yesterday, along with having Treasury provide annual reports on big government programmes and reintroducing performance pay for public sector chief executives and expanding it to their deputies.
Hipkins told Morning Report National needed to be up front with Kiwis about exactly what it was they would cut.
"At the moment all we get from National is bumper sticker slogans and marketing exercises.
"We haven't actually seen any detail from them about what they would actually do if they became the government and I'm not surprised that New Zealanders are finding it difficult to trust them," he said, referring to the latest polling.
Hipkins said people could already see their tax information by looking on their Inland Revenue account, and departmental performance was best driven by ministers.
Taxpayers "absolutely" deserved to know where their money was going and the information released by Treasury may not be accessible to the average consumer, he said, "but there's a lot of effort put in to producing summary information".
"If people want to see that little pie chart - how much money goes into health, how much money goes into education, like you do when you get your rates bill - it's all on the Treasury website, anyone can look at it at any given moment.
"If you want to know how much tax you've paid, you can look that up on myIR at any moment and that is your own tax record that will tell you how much tax you've paid."
Willis told Morning Report it was all about accountability.
"This is all about delivering more effective results for taxpayer money and making sure the government is accountable to taxpayers for how we spend your hard-earned money."
She acknowledged the information was already available but said it should be easier for taxpayers to understand.
"You could trawl quite a few government websites to work out what proportion of taxpayers' money goes where but we think we should make it easy for you, you should be able to go on your myIR page or get an email."
She said she thought it was useful information the public would be interested in.
"The aim here is not outrage, the aim here is just clear, transparent reporting.
"I think it is useful information, we want a report card that also shows what proportion of tax is going towards debt servicing and how much more money the government is spending from one year to the other. This is information a lot of New Zealanders don't have and it's really critically important that they do have it.
"Spending has gone up a billion dollars a week and the question I am most commonly asked is 'what have we got to show for it, where has it all gone'."
AI should also be used, she said.
"While it may have sounded flippant I'm quite serious. Actually, part of what I think government in 2023 should be doing is using the best technology available to ensure that all the data we're collecting across government is actually of use to your everyday person."
Hipkins said it was not new that the National Party believed the government was wasting taxpayer money - but they had yet to show how they would do better.
"On a daily basis the National Party are constantly pointing out areas where they think we should be spending more money, so this is not a new position from the National Party. They seem to think that you can increase the amount of spending whilst reducing the amount of spending at the same time.
"They don't seem to be actually providing any detail about where those cuts are going to come from and taht means that services that New Zealanders rely on, on a daily basis, like health, like education, like the welfare system, they could all be at risk."
National's finance spokesperson Nicola Willis last week said the party would put out its costings once Treasury had delivered its pre-election economic and fiscal update.
Hipkins suggested that would be too late.
"In reality, I think they need to actually put out their plan. When we were in opposition before the 2017 election we put out a plan many months before the election as to what our priorities were, what we were going to fund.
"We updated it when the pre-election forecasts came out, National are saying New Zealanders will have to wait till less than a month before the election before they know exactly what it is that they are proposing to do."
On performance pay for chief executives, he said the idea had proved ineffective.
"There was a form of performance pay for departmental chief executives under the previous National government and they almost always got the bonus regardless of the performance of the department so it was a symbolic exercise - it didn't really actually drive perfomance or change anything."
Performance instead should be driven through performance targets, but shifting those could take time.
"If we want to turn those kinds of numbers around we actually have to take a long-term view of it."
Finance Minister Grant Robertson revealed last week the government had found $4 billion in savings to keep government spending down in this year's Budget, due out Thursday.
Hipkins brushed off suggestions this proved National's criticisms that much of the government's spending was not necessary.
"We've already reprioritised that money, they can't reprioritise it again in cutting the things that it's been reprioritised towards."