Steven Joyce is standing by his claim of a $11.7 billion hole in Labour's budget, despite numerous economists saying the National finance spokesperson is wrong.

Labour's finance spokesperson Grant Robertson has demanded an apology, calling Mr Joyce's claim a "patently false and cynical attack".

But Mr Joyce doubled down on The AM Show on Wednesday morning, saying his costing calculation is the truth - and he believes Labour knows it.



"They've now proposed to change that so we didn't know anything about this so called zero budget until now and that's what they've said."

"The reality of it is, I called them because they've mucked up their operating allowances. They've now changed their story and said well that's alright because we're going to have these zero budgets outside of education and health for two years. That's just not believable, that's saying you won't pay any extra pay for police... [it's] more than really tight.

"They're dreaming."

Mr Joyce says no economist actually disagreed with him.

"They didn't say that [they disagree]. Let's get past that. The important bit is the fact that this proposal from Labour, they've already admitted they'd push debt up by about $8 billion."

Mr Joyce says leading economist Cameron Bagrie was on side with him, despite Mr Bagrie saying "there's no hole" when Newshub asked if Labour had made a budgeting mistake.

"In terms of Cameron Bagrie you've actually sort of paraphrased. He sat on the fence. He said on the one hand he will not say it's a hole, but on the other hand he's looked at their budget as they're now presented it and go, woah this is hugely challenging and unlikely to be achieved," Mr Joyce says.

But Newsroom Pro economist Bernard Hickey then told The AM Show that despite Labour's numbers being tight, Mr Joyce's numbers were too extreme.

"He came out with a big hiss and a roar on Monday and said, '$11.7 billion, it's an accounting error, it's a basic mistake, they haven't rolled forward their operating allowances'. But when we spoke to Labour it's clear that a big chunk of that money is captured in their lines for health and education.

"He really is the minister that cried wolf here, but he is right - it is tight, outside of health and education for the first two years."

Newshub's political editor Patrick Gower says the National finance spokesperson's claims are politically motivated.

"He's wrong. There is no hole. He has overcooked it.

"Forget he is the Finance Minister, he's also the campaign manager. Steven Joyce's calculator is not broken. Steven Joyce is a successful businessman and Finance Minister… he hasn't got the numbers wrong, he hasn't made a mistake. Everything he does has a reason."

Mr Joyce's old university exam results sheet has re-emerged amid the debate, showing he didn't pass eight economics papers. Many on social media are joking that maybe he simply hasn't improved at economics since then.