The National Party has admitted only 3000 households will get the full $250 a fortnight tax cut they have been campaigning on, but has always been clear that is the maximum entitlement.
The party's finance spokesperson, Nicola Willis, said she utterly rejected claims they have misled New Zealanders.
Labour finance spokesperson Grant Robertson, in a media release on Thursday morning, said only 0.18 percent - or 3000 families - would get the full $252 a fortnight in tax relief.
"National have been scamming New Zealanders about their number one policy in this election," he said, warning National's claim an "average-income family with children" would receive $250 a fortnight was "a lie".
Willis told Midday Report host Charlotte Cook the 3000 figure was correct, but said National had always been clear that was the maximum amount.
"They are a complete beat-up. So, National has been very clear that if New Zealanders want to know what tax relief they are due under our tax plan, it will depend on their individual tax plans and circumstances," she said.
"It is wrong to say that it is a scam and it is wrong to say that it is a lie."
She said the party's tax relief - as laid out in their tax plan in August - came through a mix of sources.
"What we have said - and this is absolutely correct - is that New Zealanders with a family are eligible for up to $250 a fortnight in tax relief under our plan.
"So that accounts for around 3000 families, that is why we have said if you want to know how much you're getting under our tax plan, go to National tax calculator."
She said she utterly rejected misleading New Zealanders, and did not think people would be surprised to find out they may not get the full $250.
"How much you get depends on your circumstances, if you don't have young children, you won't be getting that FamilyBoost payment ... you'll be getting income tax reduction of up to $50 a fortnight, but we've been consistent in saying how much you get depends on how much you earn."
In a statement, Willis said more than 250,000 New Zealanders had used National's tax calculator to find out how much they would receive, and "New Zealanders are telling us they want tax relief".
"Our plan is carefully targeted to ensure that those who will benefit the most are working New Zealanders. It's about time they got some relief," she said.
Robertson's statement had said 99 percent of households would not get the full $250 a fortnight.
"Christopher Luxon will say anything to get elected and that includes misleading New Zealanders about the size of their tax cuts," he said.
He continued to criticise National's refusal to disprove economists' calculations showing its foreign buyers tax would fail to provide anywhere near as much as the party said it would.
"It is unprecedented for a major party's flagship policy to have been so thoroughly discredited in an election campaign. Christopher Luxon can't chopper-in John Key to try to sort this shambles out.
"With 10 days until polling closes, New Zealanders need to take a closer look at National's tax scam. It's a house of cards that is rapidly collapsing."
Labour leader Chris Hipkins also started a media briefing on Thursday afternoon with fresh comments on the issue.
He said the impression Kiwi families had been given "goes right to the heart of Christopher Luxon's integrity. He's been scamming New Zealanders about their number one policy in this election and now they've been exposed for that".
Hipkins said Labour announced a new scammer policy today.
"Little did we know we were going to need it quite so soon."
Speaking to media on Thursday afternoon, National Party leader Christopher Luxon rejected suggestions National had been disingenuous with its tax policy.
"What we've said is up to $250 a [fortnight] for an average household income with young children ... what I'd just say to you is when you look at the aggregate of our tax plan, and you actually look at the delivery of what we're offering low and middle income New Zealanders, we are going to give them tax relief and it's really important that we do that.
"It depends on what your income earning is. We modelled it out completely at a different range of salaries and revenues ... what we've got is a significant amount of tax relief for our low and middle income New Zealanders.
"We've always given a range."