How-to-vote cards are small leaflets that are handed out by party supporters during elections in Australia. Voting in the Australian lower house uses a preferential voting system. Voters must rank every candidate on the ballot in order for their vote to count. There are often numerous candidates on the ballot, some with little public profile, so voters may find it difficult to decide on all of them. Parties produce how-to-vote cards ostensibly to help voters. They contain details about the candidate or party as well as instruction how to cast a ranked vote in the order that the party would prefer the voter follow. The flow of preferences can assist the party dispersing the cards directly and indirectly help allied parties.
The use of how-to-vote cards has benefited minor parties in a number of ways including increasing their chances of winning, punishing opponents and receiving policy commitments. Sometimes "preference deals" are done between political parties so that they are favoured by each other's how-to-vote cards.
Voters are under no obligation to follow the cards. In South Australia, all how-to-vote cards are displayed on all polling booths.