The new Government could be formed by any one of a variety of arrangements agreed between parties.

The options include a formal coalition agreement, a confidence and supply agreement or even by a party's preference to abstain on confidence and supply votes which face the Government throughout the year.

If, for argument's sake, New Zealand First agreed to abstain on confidence and supply votes in exchange for a raft of policy concessions by National, National's 58 votes would beat Labour and the Greens' 52 no-confidence votes on crucial votes and allow National to govern.

It is likely a deal with the agreement to actively support the Government on confidence and supply votes would entitle the smaller party to ministerial positions.

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Since 2005, Labour and National governments have used this model.

A formal coalition agreement with all parties in a Cabinet would mean all parties agreeing to Cabinet collective responsibility and would give the partner parties a great ownership stake in the Government.

New Zealand First's coalition agreement with National in 1996 was very detailed and explicit.

Confidence and supply agreements in recent years have set out some policies but have also set out processes by which the partner parties maintain sound relationships.

There is not an explicit deadline by which a new Government must be formed but the Governor-General could exercise reserve powers to call a new election if a protracted stalemate ensued.

There are some marker dates however which may act as an incentive.

October 12 is the day fixed for the return of the writ - the day electorate MPs are formally announced - and is followed by a declaration of list MPs, although this date may be postponed if there are recounts.

November 23, being six weeks after writ day, is the day by which Parliament must meet and acts as an incentive. If no government has been formed by then, a vote on the address-in-reply, which is held after the opening of Parliament, is the first opportunity for a confidence vote.

If that vote does not make things clear, the Governor-General is then likely to call a new election.

In 1996, Parliament was required to meet by December 13, coalition talks concluded by December 10, the National-New Zealand First agreement was signed on December 11 and the opening of Parliament took place on December 12 and 13.