# Majority jackpot system

The majority jackpot system (MJS), also known as a majority-minority apportionment, is a mixed-member majoritarian and conditional voting rule. It produces subproportional representation by fixing the final apportionment for a party or alliance that wins a majority of the vote at some level (e.g. 55% of the seats). It differs from the similar majority bonus system in that the total number of seats is fixed, whereas the majority bonus assigns a fixed number of "bonus" seats to the majority party.
It is currently used in Armenia and San Marino, and was previously used in Italy from 2006 to 2013.
An example of a very small, almost insignificant majority jackpot type correction system is found in Germany's electoral system for the Bundestag. If a party receives more than half of the list votes, but does not receive more than half of total seats (for example, as a result of the apportionment formula), they receive as many seats as necessary, which are added to the size of the Bundestag.

## History

Benito Mussolini was the first politician to enact a law to give automatic seats to the winning party and ensured his victory in the 1924 Italian general election. The system was reintroduced for the 1953 Italian general election, in which any parliamentary coalition winning an absolute majority of votes would be awarded two-thirds of the seats in Parliament. The Christian Democracy-led coalition fell narrowly short of this majority in the election, and the system was abolished before the 1958 election.
A similar plurality jackpot system, which awarded 55% of seats to the largest party, was introduced for local elections in 1993 and national ones in 2006 (replacing scorporo). In the 2013 Italian general election, the Democratic Party won 292 seats in the House using its 8,644,523 votes and so needed 29,604 preferences to obtain a seat. Its major opponent, The People of Freedom, won 97 seats with 7,332,972 votes and so needed 75,597 votes for a single seat. The system in use in Italy from 2006 until 2013, which assigned the jackpot to the plurality party (even if they lacked a majority), was judged unconstitutional by the Constitutional Court of Italy. After a proposed modification involving a run-off vote (between the top two alliances) was also struck down, parallel voting was adopted for the 2018 Italian general election.

## Jackpot vs. bonus

The jackpot system ensures the winning party or alliance ends up with at least a certain fixed number of seats in total, by granting it however many additional seats are needed. In the Sanmarinese Parliament, the majority alliance is given 35 out of 60 seats. A majority jackpot system can be seen as a variant on the (compensatory) additional member system, where a set of seats are assigned by the plurality principle (but in case of the jackpot system, in a multi-member district), while the rest of the seats are assigned with the proportionality principle, taking into account the seats already distributed. This means if the majority jackpot is set at 55%, and the largest party/coalition receives 35% of the vote, they will be entitled to the additional 20% to reach 55%, but no more. The rest of the seats are distributed among the other parties, unlike the majority bonus system, which would not take them into account (like parallel voting). If the largest party would receive 60% of the vote, they would be entitled to the additional 5% of seats above the majority jackpot, unless there is also a minority jackpot. The size of a jackpot is typically above 50%, to provide for a clear majority, but may also provide for a certain size of supermajority.
| Size of jackpot (%) | Vote share of the largest party (%) | Vote share of the 2nd largest party (%) | Appr. seat share of the largest party (%) | Appr. seat share of the 2nd largest party (%) | Effective bonus for largest party (%) | Effective bonus for second-largest party (%) |
| 50% | 35% | 25% | 50% | 19% | 15% | -6% |
| 55% | 35% | 25% | 55% | 17% | 20% | -8% |
| 60% | 35% | 25% | 60% | 15% | 25% | -10% |
| 50% | 45% | 25% | 50% | 23% | 5% | -2% |
| 55% | 45% | 25% | 55% | 20% | 10% | -5% |
| 60% | 45% | 25% | 60% | 18% | 15% | -7% |
| 50% | 55% | 25% | 55% | 25% | 0% | 0% |
| 55% | 55% | 25% | 55% | 25% | 0% | 0% |
| 60% | 55% | 25% | 60% | 22% | 5% | -3% |
The table below shows the difference between the jackpot and bonus rules.
| Size of bonus (%) | Size of jackpot (%) | Vote share of the largest party (%) | Appr. seat share of the largest party (%) | Appr. seat share of the largest party (%) | Effective bonus |
| Size of bonus (%) | Size of jackpot (%) | Vote share of the largest party (%) | Bonus system | Jackpot system | Effective bonus |
| 10% | | 45% | 51% | | 6% |
| 25% | | 45% | 59% | | 14% |
| 50% | | 45% | 73% | | 28% |
| | 50% | 45% | | 50% | 5% |
| | 55% | 45% | | 55% | 10% |
| | 60% | 45% | | 60% | 15% |
| 10% | | 55% | 60% | | 5% |
| 25% | | 55% | 66% | | 11% |
| 50% | | 55% | 78% | | 23% |
| | 50% | 55% | | 55% | 0% |
| | 55% | 55% | | 55% | 0% |
| | 60% | 55% | | 60% | 5% |
The jackpot system essentially gives the size of the jackpot or the vote share (whichever is higher, making it a conditional system and an effectively flexible "bonus"), while the bonus system gives a fixed bonus (in terms of seat numbers, which mean slightly variable effective bonus in terms of percentages) and a proportional share of the rest of the seats. The jackpot only modifies the seat share when the largest party's proportional seats count based on its vote share is below the size of the jackpot. A jackpot system may also have further conditional elements: it may provide for a supermajority jackpot only for a party which received an absolute majority of vote.

### Minority jackpot

A variant on the majority jackpot is the minority jackpot, which ensures a certain amount of minimum representation for political or minorities. A variation of the minority jackpot is lower threshold for certain minority lists or reach their first seat.

## Use

| Country | Type of election | Type of system | Size of jackpot | Notes |
| Armenia | national elections (legislative) | conditional majority jackpot (two rounds) | 54% | Second round is held if no party reaches 54% of seats and no coalition government can be formed If a party would receives more than 2/3 of seats, their share is capped at 2/3, all minority parties must have at least 1/3 of seats in total. |
| Armenia | national elections (legislative) | minority jackpot (compensatory) | 33% | Second round is held if no party reaches 54% of seats and no coalition government can be formed If a party would receives more than 2/3 of seats, their share is capped at 2/3, all minority parties must have at least 1/3 of seats in total. |
| Djibouti | national elections (legislative) | plurality jackpot | 80% | Used in multi-member district. |
| Germany | national elections (legislative) | conditional majority jackpot | exact majority ("50%+1") | If a party received more than half of all list votes, but did not receive more than half of all seats, as many seats are added for that party, as necessary (these would increase the size of the Bundestag slightly, in case it would be used) |
| Italy | provincial elections | conditional majority jackpot (two rounds) | 60% | Using a double simultaneous vote with the presidency. If no list wins more than 50% of the vote, a runoff is held with a majority jackpot of 60%. |
| Italy | municipal elections above 15 000 inhabitants | conditional majority jackpot (two rounds) | 67% | With 2 votes cast, the second vote is for the jackpot and also functions as a double simultaneous vote with the mayoral race. Split ticket is allowed. |
| San Marino | national elections (legislative) | conditional majority jackpot (two rounds) | 55% | |