An overhang happens when a party wins more electorate seats than its party-vote share entitles it to. Those MPs keep their seats, so Parliament grows slightly beyond 120. Every overhang seat also raises the number of MPs needed for a majority, which can quietly change who is able to form a government.
An overhang happens when a party wins more electorate seats than its party-vote share entitles it to. Those MPs keep their seats, so Parliament grows slightly beyond 120. Every overhang seat also raises the number of MPs needed for a majority, which can quietly change who is able to form a government.
Electorate wins are always kept.
Parliament grows by the extra number.
A majority becomes harder to reach.
Overhangs are usually small, one or two seats.
Suppose a party earns 2% of the party vote, which is worth about two seats, but wins four electorates. It cannot be asked to give two electorates back, because voters in those places chose those people.
So Parliament simply gets bigger for that term.
With 120 MPs, a majority is 61. With a two-seat overhang there are 122 MPs, and a majority becomes 62. On a close election night, that single number can decide who governs.
How often does an overhang happen?
It has happened several times since MMP began, usually adding one or two seats.
Does the extra MP have less power?
No. They are a full MP with a full vote.