The new Government won't have enough change left over from meeting its policy promises to meet operating costs, National says.
Bill English said today's half yearly accounts from Treasury showed Government debt would increase over the next five years.
English spoke to media shortly after the National Party Twitter account posted a photo of Finance Minister Grant Robertson as a Grinch, stealing National's planned tax cuts.
"It looks very tight out over the next few years for Labour to meet their debt targets – just as we predicted," English said.
"They have got quite limited future allowances for the very large number of other promises they are yet to fund…you will see the rest of the shortfall in the Budget.
"They don't have any room to do any more later. They have used it all up."
Finance Minister Steven Joyce was asked about his claim during the campaign that Labour had a multi-billion dollar fiscal hole, and said today's books showed he was right.
"Yes, I think it does. It is just incredibly tight over the next few years…they have given themselves very little room."
Joyce said in his view there wouldn't be enough money left over to keep the Government running.
"They might be able to meet some if not all of their commitments. But in terms of general government expenditure…there is very little left over…they have left themselves no room."
Treasury's Half Yearly Fiscal Update today set out its revised forecasts under the new Government.
Labour also used it to cost the policies of the first 100 Days programme, including releasing the final shape of its major Families Package, most of which will come into effect in July 2018.
That package is forecast to almost halve the number of children living in poverty, and was introduced in place of National's planned tax cuts.
The National Party tweeted a picture of Finance Minister Grant Robertson stealing presents from below a Christmas tree, labelling him, "the Grant that stole Christmas".
Robertson defended drawing down more debt to re-start contributions to the Super Fund - which would begin with an immediate $500 million injection.
"We think this is an important signal that we are prepared to invest in future generations now. There is a shared commitment across the coalition to keep superannuation eligibility at the age of 65. This is a contribution to doing that and one we believe is important."
Although its borrowing would almost hit $70 billion, it was on track to get below 20 per cent by 2022 - slower than National had planned but within Labour's own target.