The 150 members of the
National Council were elected by
proportional representation in a single nationwide constituency with an
electoral threshold of 5% for single parties, 7% for coalitions of two or three parties, and 10% for coalitions of four or more parties. The election used the
open list system, with seats allocated using the
Hagenbach-Bischoff system. Voters were able to cast up to four preferential votes for candidates on the list of the party they voted for. All participating parties must had register 90 days before election day and paid a
deposit of €17,000, which would be refunded to all parties having gained at least 3% of the votes. All citizens of the Slovak Republic were allowed to vote except for
convicted felons in prison (only those who were convicted for serious offences), people declared ineligible to perform legal acts by court, and citizens under 18 years of age. All citizens, who were 21 years of age or older on the election day and are permanent residents of Slovakia, were allowed to run as candidates except for
prisoners, convicted felons, and those declared ineligible to perform legal acts by court. Voters abroad on election day were allowed to request a
postal vote. According to the Central Election Committee, approximately 20,000 citizens of the Slovak Republic living abroad had requested a postal vote for the election. The deadline for requests passed on 10 January 2020. ==Political parties==