As National and Labour ready their negotiating teams to sit around the table with Winston Peters and NZ First, identifying areas of policy compatibility - and incompatibility - will be at the top of their minds.
Figuring out where the major parties sit ideologically in relation to NZ First is easy enough: broadly speaking, Labour may fare best in areas like foreign ownership, education and immigration, while National could be better placed on law and order, welfare and Maori issues.
Beyond any baubles of office, the hardest part will be accommodating some of the minor party’s policies while making the budget work.
With both National and Labour pledging to maintain an operating surplus and reduce government debt to 20 per cent of GDP (the former by 2020, the later by 2021/22), any large new commitments will force some juggling and re-prioritisation of their own plans.
While Steven Joyce’s claim of an $11.7 billion “fiscal” hole in Labour’s plans was widely laughed out of town, it’s true that Jacinda Ardern and company have little room to move in terms of new spending commitments (although the same is true for National to a lesser extent).
Pinning down Peters on the fiscal particulars is also a difficult task, as RNZ’s Guyon Espiner found out during a now legendary Morning Report interview.
So which policies will be the easiest to fit into the books, and which will cause the greatest headaches?
Billions of promises
During that interview with Espiner, Peters estimated his party’s policies would cost roughly $10 billion in investment and borrowing over “about seven to eight years”.
However, NZ First’s tertiary education policy alone - which includes a universal student allowance and wiping student loans for those who stay and work in New Zealand was estimated to cost $4.6b a year at the party’s regional conference in June.
Both National and Labour said at the time the policy was unaffordable; Labour has costed its own plan of three years’ free tertiary education at $265m in the first year, rising to $1.2b once fully implemented.
Another hefty policy is NZ First’s pledge to take GST off “basic food”.
The party’s own website said that would cost $3b a year, but Peters told Espiner the actual cost would be between $600m and $700m.
The ambiguity around what counts as “basic food” makes this one a little hard to cost, but NZIER estimated Labour’s 2011 pledge to take GST off fresh fruit and vegetables as costing nearly $250m a year.
A promise to cut the corporate tax rate to 25 cents would cost about $2.5b, Peters told Espiner, although some estimates have put it lower, at about $1.4b.
Giving local government the GST from foreign tourism would cost $1.5b a year in lost revenue, the party estimates.
Then there is Peters’ pledge to move container operations from the Ports of Auckland to Northport, near Whangarei, within 10 years.
Kiwirail has estimated simply upgrading the Auckland to Northland rail line would costs billions of dollars, while a Port Future Study released in 2016 estimated the cost of moving the port to the Manukau Harbour or the Firth of Thames at between $4b and $5.5b.
Those headline policies alone take you into the billions of dollars. Then there are policies which could have a significant but less tangible impact on the economy, such as cutting immigration levels and renegotiating free trade deals.
Less room for Labour to move
With Labour, there are some policy overlaps that would make life easier for Ardern, such as free driver’s licence training and testing for students, as well as a move to 26 weeks’ paid maternity leave.
However, the party’s fiscal plan gives it only $3.2b in unallocated spending over the next three years, compared with $4.2b for National by its own calculations.
With Ardern recommitting to Labour’s budget responsibility rules, that could make life harder for her when it comes to meeting Peters’ demands, as Interest.co.nz’s Alex Tarrant has noted.
Bill English and his team would also have to make some spending changes if it was to adopt a significant number of NZ First’s policies.
There are smaller ticket policies that could carry a heavier symbolic weight, such as fulfilling Peters' pledge to properly fund smaller regional airports (estimated by the New Zealand Airports Association to cost $32m over five years).
Labour or National could also boost their own police promises to meet NZ First's target of 1800 sworn police (Labour estimates its plans to gradually hire 1000 sworn police to cost $40m a year).
However, whoever Peters crowns, they will have likely paid their price in gold.