Comment: Overhang has become MMP's biggest problem, and the 2026 result shows why

HouGarden New Zealand, 12 November — This is a comment piece. The views are those of the author, Mark Thomas, who was a candidate for Wellington Central at New Zealand's first MMP election in 1996 and is now based in Auckland. They are not established fact or official positions.

Some background is needed first. The figures below are preliminary results from the 2026 election, not final ones. Official results may change the size of the overhang and its political consequences. Under MMP, voters have two votes: a party vote and an electorate vote. The party vote is meant to decide each party's share of Parliament.

Thomas says New Zealand has spent three decades accommodating the compromises of MMP. In his words, most have been manageable, occasionally controversial, but rarely decisive. He argues the 2026 election has exposed one that can no longer be ignored.

Overhang is the issue. It occurs when a party wins more electorate seats than its party-vote share entitles it to. Under current law the party keeps every electorate win, and Parliament grows to make room. This is different from Germany's compensatory seats, which are extra seats awarded to restore proportionality.

On the preliminary results, National's party vote would ordinarily entitle it to 35 seats, but it has won 42 electorates. Te Pāti Māori (the Māori Party) would be entitled to one seat on its party vote, but has won five Māori electorates.

The resulting overhang is 11 seats. It benefits two parties on opposite sides of politics. It would expand Parliament from a nominal 120 seats to 131. The Parliament just gone had 123 seats because of a smaller Te Pāti Māori overhang.

Thomas argues this is more than a matter of size. He says the overhang could determine who governs, even though MMP's aim is that the party vote should decide the proportional balance of Parliament. Overhang first appeared in 2005, and in his view it could now undermine the central promise of the system.

He separates overhang from strategic voting. Strategic voting is when voters back an electorate candidate from another party to influence the wider result. Across 11 MMP elections and 767 electorate contests, Thomas says only a handful of cases clearly show organised tactical voting achieving its aim. The best known are Wellington Central in 1996, Coromandel in 1999 and Epsom from 2005.

Other candidates have drawn support from voters whose party preference lay elsewhere. Thomas names Jim Anderton, Peter Dunne, Winston Peters, Chlöe Swarbrick and Tamatha Paul. He says this often reflected views of the candidate rather than strategic calculation. This year in Tāmaki, an explicit appeal for cross-party electorate support failed, with ACT finishing third.

Split voting, he says, is a legitimate feature of MMP. Voters can back one party nationally and a candidate from another locally. Strategic voting is one way of using that freedom, and not a defect in the system. Overhang is fundamentally different.

The 1986 Royal Commission anticipated overhangs but thought them unlikely. When they began appearing in 2005, they added one or two seats. They came mainly from Māori electorate victories and did not affect overall government formation.

Thomas lists other unresolved questions that have been absorbed over three decades. They are the 5 per cent party-vote threshold, the electorate-seat exemption (under which winning one electorate lets a party into Parliament without reaching the threshold), the balance between electorate and list MPs, and the continuing role of the Māori electorates.

He draws a line between accepting democratic compromises and tolerating a mechanism that can overturn the proportional balance of an election.

Germany, whose system helped inspire New Zealand's, has already faced the problem. Its Bundestag had a statutory base of 598 seats. Overhangs and the compensatory seats added to restore proportionality pushed it to 736 members by 2021.

Reforms first applied in 2025 fixed the Bundestag at 630 seats. They removed both overhangs and compensatory seats. Party votes now decide each party's entitlement, even if some constituency winners miss out. In 2025, 23 candidates received the most votes in their constituencies but did not enter Parliament, because their parties lacked enough party-vote support.

Thomas accepts that many New Zealanders might find that hard to accept. But he says Germany made an explicit choice: proportionality and a fixed Parliament would take precedence over guaranteeing every constituency winner a seat. New Zealand, he says, has made the opposite choice. It protects electorate winners at the cost of proportionality and a predictable parliamentary size. In his view, these principles cannot all be preserved: "Something has to give."

Two earlier reviews have looked at the issue. The Electoral Commission's 2012 review recommended abolishing additional overhang seats and the one-electorate-seat threshold, and lowering the party-vote threshold to 4 per cent. The 2023 Independent Electoral Review proposed a 3.5 per cent threshold. It also recommended replacing additional overhang seats with fewer list seats.

Thomas says that approach would keep electorate winners and stop Parliament expanding, but could reduce proportionality. Neither review's recommendations were implemented. Reform is therefore only being called for at this stage. Nothing has been decided.

He adds that Germany's solution has costs. It challenges the expectation that winning an electorate guarantees a seat in Parliament. He says this has particular implications for the Māori electorates.

Thomas also raises a wider question about how well MMP represents New Zealand. He cites David Farrar's provisional analysis of the incoming Parliament, which shows large demographic gaps.

Māori and Rainbow communities have roughly twice their population share in Parliament. Asian New Zealanders have less than half theirs. Pacific representation also falls short.

Age is also skewed. Two-thirds of MPs are in their 40s and 50s, though those age groups make up only one-third of New Zealanders aged 20 and over. People in their 20s and 30s hold 17 per cent of seats, but make up 37 per cent of that population. Those aged 70 and over are about 15 per cent of that population but just 1 per cent of MPs.

Thomas calls these significant differences for an institution meant to represent the country. He accepts that Parliament can never mirror every demographic trait, and that overhang is only one contributor. Parties and voters, he says, are responsible for whom they recruit, select and vote for.

Even so, he says MMP was introduced to make Parliament both more proportional and more broadly representative. Three decades on, he argues, overhang is undermining the purpose of the party vote, while the demographic gaps show how uneven representation remains.

He says the official results may change this year's overhang and its political consequences, but not the underlying problem. He also argues reform should not become another fight over partisan advantage. Overhang has persisted under successive governments and now affects parties across the political spectrum.

Thomas says New Zealand must now make the choice Germany made. If proportionality is no longer paramount, he says, "we should be honest about that" and reconsider the electoral system the country wants. But only 29 per cent of New Zealanders favoured a different electoral system in an August poll. He concludes that the challenge is to reform MMP, not replace it.

After two substantial electoral reviews, he says, what is needed is a final, cross-party process backed by the major parties. It should resolve MMP's competing principles and deliver reform, recognising that there will inevitably be winners and losers.

Strategic voting, he says, will keep coming and going in individual electorates as a legitimate expression of voter choice. But when overhangs benefiting either side of politics can determine who governs, they undermine the proportionality MMP was designed to deliver. In his view, what was a minor electoral compromise has become one with major consequences.

Thomas ends with this warning: after 30 years of MMP, New Zealand cannot afford to leave the integrity of its electoral system hanging.