National will face some roadblocks from its Government coalition partners during negotiations when it comes to establishing its ideal economic policies, according to an economist who believes the talks will involve "lots of calculators". 

Economists have been wracking their brains over how negotiations are set to shape the incoming Government's economic policies.

ANZ's latest economic outlook examined the fiscal outlook for the incoming National-led Government and noted that the addition of ACT and NZ First could lead to more significant changes.

Talking to Heather Du-Plessis Allan Drive on Thursday, Infometrics principal economist, Brad Olsen said one policy he couldn't see getting lost in the negotiation whirlpool was National's bottom-line election promise of income tax cuts. 

"I just don't see any possibility where National can't deliver tax cuts, they have to - that was the mainstay of their economic agenda and actually the mainstay of their entire political agenda," he reassured Du-Plessis Allan. 

"People voted for them and said look I'm voting you in so you can give me a tax cut. So in my mind, they've got to deliver them but of course, that's money which is tight at the moment."

He noted before National was elected, Labour's treasury had warned of a $2 billion hole in the budget books, which was more than the public had been expecting. It meant there was a struggle to fund all the proposals of the Labour-led Government. 

"Bringing on something like those tax cuts is expensive, so the question is, where does that money come from - and, what other policies do the other parties want."

Olsen was asked if it was safe to assume the money to cover National's tax cut plan wouldn't be funded by the Foreign Buyers' tax, given NZ First and ACT weren't keen on that particular source of revenue. 

"Well, that's the complication of this," he responded. 

"Winston Peters and NZ First were part of the Government which instigated the Foreign Buyers ban, so it seems a bit hard they'd be super keen on the Foreign Buyers tax at the same time - that's what's been funding it."

Olsen said when the Government took the stance of cutting back on services and costs to generate more revenue, the amount that would be cut would differ depending on each party's view. 

"National wanted to do more than Labour was already doing, but ACT wanted to go a bit further than that," he said. 

"There will be a lot of negotiations, a lot of calculators being pulled out in the negotiations as they go through."

On interest deductibility for landlords, Olsen said a key focus for negotiations will be how this policy would be rolled out - given ACT were keen to introduce it for landlords quickly but National had outlined its desire to introduce it in stages. 

NZ First had also expressed keen interest in doing so but hadn't provided much clarity on how quickly. 

"I think it's almost indicative of this entire conversation - we know, sort of, what Lego kit we've bought but don't know how quickly we'll build it and exactly what parts will come through at what point," said Olsen. 

"Because all three parties want that interest deductibility, again, that's money which is effectively an expense which the Government has to account for."

One thing Olsen said was a safe bet would be seeing National's desire to increase the superannuation age tossed out during the coalition discussions. 

"That, I think, is the easiest one to give away," he said. 

"When have you ever heard a politician who's been absolutely do-or-die on raising the New Zealand super-age? It seems like something to be kicked out of negotiations all the time, it just seems as though it's too difficult and too hard to get through."