Explainer: What You Need To Know About How MMP Works

Russell
Palmer Political reporter

Explainer
– Our MMP electoral system is marking its 30th
anniversary this year, but it can still be tricky to explain
exactly how it all works.

If you’re confused about all
the recent talk about overhangs
and party votes and just want to know what you’re deciding
on at the ballot box, here’s what you need to know about
voting and MMP.

What is MMP?

MMP stands for
Mixed Member Proportional representation, the electoral
system used in New Zealand.

A majority of New
Zealanders voted for it – twice, first in a non-binding
referendum in 1992, and again in a binding referendum at the
election the following year. It was introduced at the next
election, in 1996.

National’s leader Christopher Luxon
has proposed
another referendum over MMP, to be held after the 7
November election.

MMP aims to ensure that people will
be represented in Parliament both by a person in their local
area (electorate) and by a group (a political
party).

How does it work?

New Zealanders have
two votes – one for a local representative, and one for a
political party. You just pick the person in your electorate
you think best advances your interests, and the political
party that best represents your interests.

Simple,
right?

The complexity comes in when trying to
calculate how these votes translate into the seats available
for members of Parliament (MPs).

There are (typically)
120 seats:

• 72 are electorate
  seats and are won by candidates standing in specific
  areas
• 48 are list seats and are
  allocated depending on the proportion of party votes won,
  taking into account the number of electorate seats each
  party has won

Basically, it all means that the
proportion of party votes should be about the same as the
proportion of seats in the Parliament. Electorate MPs will
belong to one party or another unless they’re running as an
independent, but voters do not need to vote for an
electorate representative that matches their party
vote.

You must be registered – or enrolled – to be
able to vote, and unlike in previous elections this year you
will
not be able to enrol on the day, or in the two weeks
before election day.

In 2026, this means voters must
be enrolled before 25 October.

Other
things to consider

A party has to win at least 5
percent of votes or an electorate seat to win a seat in
Parliament.

If they win an electorate seat, the party
gets allocated a percentage of list seats based on their
party vote – known as the “coat tail” rule.

If a party
wins more electorates than its share of party votes allows
for, extra seats can be added to the Parliament to make up
for
the “overhang” and ensure the proportions remain closer
to the party vote than they would otherwise.

For
instance, this meant there were 121 MPs in 2005, 122 MPs in
2008, and 121 in 2011, and 123 – a record number of MPs –
after the election in 2023. It’s possible there could be
even more this year due
to some calls for “strategic voting” for party votes
over electorate candidates.

So who wins the
election?

In contrast to some countries overseas –
the United States for example – the election in New Zealand
is not voting for the country’s leader. People vote only for
the parties and electorates.

But someone has to be in
charge. Someone has to make sure the organisations doing all
the management of the country – funding hospitals and
schools, repairing roads and infrastructure, managing
prisons – all that administrative stuff, and more, is being
done properly.

This responsibility – and the power it
entails – belongs to the government.

Who gets to
become the government is basically whichever party can get a
majority – more than 50 percent – of the seats, based on
their party vote. If none of the parties has enough to reach
more than 50 percent, they must negotiate with each other
about their plans until a combination of the parties has at
least half the seats.

This can result in a coalition –
where the bigger party and smaller party form a government
together and come up with a complete policy plan – or a
confidence and supply agreement, where the smaller parties
agree to support the main governing party on specific
policies.

Under confidence and supply, the smaller
party does not need to support policies that fall outside
the agreement.

With 50 percent of the seats in
Parliament, the governing party or coalition can decide what
to change about how the country works and enact these
decisions in Parliament. We currently have a coalition
government between National, New Zealand First and
ACT.

The governing parties have most of the power. The
parties that are not governing are known as the opposition,
and it is their job to criticise and poke holes in the plans
the government is putting forward.

Will
MMP ever change?

Not everyone likes MMP, and
National’s leader Christopher Luxon is campaigning
on holding a referendum on it – to test whether the
public still supports the model.

This would be the
fourth public vote on changing the electoral system. A
consultative referendum in 1992 indicated public appetite to
change the system from the previous First Past the Post
approach, and a binding referendum a year later in 1993
confirmed that, prompting the shift to MMP.

At the
2011 election, another
referendum asked whether voters wanted to keep MMP or
replace it, and what system would be preferred if it was
changed. Almost 58 percent of voters wanted to keep it, an
increase of 3.91 percentage points over the 1993
result.

First Past the Post was the most popular
alternative, with 46.7 percent of people selecting that over
preferential voting (12.5 percent), single transferable vote
(16.7 percent), and supplementary member systems (24.4
percent).

The result triggered an Electoral Commission
review of how well MMP was working, which recommended
several changes that have largely not been taken
up.

Another review
in 2022 and 2023 by the Ministry of Justice heard from
more than 1700 groups or individuals and also recommended
multiple changes.

The National-led coalition in 2024
rejected
several immediately, and later announced
plans to restrict voting by removing
early and same-day enrolment and other
changes.

Note: This article was originally
published in 2020 but has been updated ahead of the 2026
election.

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