What is an Over Hang?
what is an overhang in the NZ Parliament is a question we have been going through the last few days:
In New Zealand’s Mixed Member Proportional (MMP) electoral system, an “overhang” occurs when a political party wins more electorate seats than it is entitled to based on its overall share of the nationwide party vote. This causes the total number of members of Parliament (MPs) to increase beyond the usual 120 until the next general election.
How an overhang works
- Dual voting system: Under MMP, voters cast two ballots:
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- Electorate vote: To choose a local MP for their constituency.
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- Party vote: For the political party they prefer. This vote determines the overall proportion of seats each party gets in Parliament.
- Party entitlement: A party’s total number of seats is based on its share of the party vote. A party that wins 10% of the party vote, for example, is entitled to roughly 12 seats in a 120-seat parliament.
- Overhang trigger: An overhang is triggered when a party wins more electorate seats than its proportional share of the vote. If that same party with 10% of the party vote wins 15 electorate seats, it receives those 15 seats, which is more than its 12-seat entitlement.
- Parliament expansion: The party keeps the additional seats because their candidates legitimately won the local elections. To accommodate this, the size of Parliament is increased by the number of extra seats. The total number of MPs for other parties is not affected.
Example from the 2023 election
- Te Pāti Māori: In the 2023 general election, Te Pāti Māori won six Māori electorate seats.
- Overhang effect: Because their party vote entitled them to only four seats, the party had two “overhang” seats.
- Result: This increased the size of Parliament from the usual 120 MPs to 122.
Consequences of an overhang
- Higher majority threshold: Because the total number of seats in Parliament increases, a governing party or coalition needs more seats to secure a majority. In 2023, the overhang meant a majority required 62 seats instead of 61.
- Increased influence for smaller parties: An overhang can give a small party, such as Te Pāti Māori, disproportionate influence. In 2023, their seats meant that the National and ACT parties needed support from New Zealand First to reach the new 62-seat majority.
