Opportunities to vote arise in five decision-making procedures:

1. Election of the President every 7 years
2. D�il (parliamentary) elections, at least every 5 years
3. Referenda on proposed Constitutional amendments
4. Election of representatives to the EU Parliament, every 5 years
5. Elections to local authorities, usually every 5 years.

Resident citizens over the age of 18 years may vote at D�il, Presidential, local and European elections, and referenda.
British citizens living in Ireland may vote at D�il, European and local elections.
European Union citizens may vote at European and local elections.
All residents, regardless of citizenship, may vote at local elections.

The electoral system is proportional representation by means of a single transferable vote (PR-STV) in multi-member constituencies. Voting in D�il elections is by secret ballot. Postal voting is confined to members of the defence forces and civil servants and their spouses serving abroad.

When voting the voter marks the ballot paper by placing the figure '1' opposite the name of the candidate of his or her first choice and, if the voter wishes, '2' is placed opposite the name of the second choice, and so on. The elector is, in effect, telling the returning officer 'I wish to vote for A, but if that candidate does not need my vote or has no chance of being elected, transfer my vote to B; if B in turn does not need my vote, or in turn has no chance of election, transfer my vote to C'.

At the opening of the count, the ballot papers are mixed together and then sorted according to the first preferences recorded for the candidates. The total number of valid papers is counted, and the electoral quota is calculated. The quota is the smallest number of votes necessary to secure the election of a candidate.

The quota is established according to the formula: Total valid votes +1 number of seats +1 Thus, if there were 40,000 valid votes and four seats to be filled, the quota for election would be 8,001 and only four candidates could reach the quota. If, on the first count, no candidate has reached the quota, the candidate who received the lowest number of votes is eliminated and his or her votes are transferred to the candidate for whom a second preference is recorded. If a candidate receives more than the quota required for election, his or her surplus votes are transferred to the remaining candidates in accordance with the subsequent preferences expressed by the electors. When the number of remaining candidates who have neither been elected nor eliminated corresponds to the number of vacancies to be filled, those candidates are declared elected. This applies even though those remaining may not have reached the quota.

An election for the Seanad takes place not later than ninety days after a dissolution of D�il �ireann. The voting system used is proportional representation by secret postal ballot.

The electorate for the forty-three members of the Seanad elected from panels of candidates, numbers just over 1,100. The electorate comprises the members of the newly-elected D�il, the members of the outgoing Seanad, and the members of every council of a county or county borough. There is a separate election for each of the five panels. The electorate for the six members elected from the universities consists of every citizen who has received a degree (other than an honorary one) from those universities and who has attained the age of eighteen years and is registered as an elector.