Whichever system is used, electoral registers should only contain the relevant data needed for elections while guaranteeing the protection of the citizens' privacy.
Across the board, the data considered necessary on an electoral register includes the voter's name, address and date of birth.
Address
The citizen's address is considered essential inasmuch as the registers are classified by territory and link the affirmation of the right to vote to a specific electoral constituency.
Problems do arise, however, when it comes to assigning an address to someone who actually does not have one, whether it be because they permanently reside outside the country or because they do not have a stable home. In cases where no permanent address can be established, electoral regulations usually provide legal alternatives to avoid any deprivation of the basic right to vote. In systems with a permanent register, for example, the solution usually consists of maintaining the last address prior to residence abroad for electoral purposes. Voters registration systems have also sought practical solutions of a legal or jurisprudence origin. Thus, for example, in the majority of the states in the United States, it is permitted to use a mail drop or a friend's address for voter registration, as long as they can be located by the United States Postal Service. This has allowed thousands of homeless people to express their right to vote who might otherwise not have been able to vote.
Date of Birth
Dates of birth are also a important from an electoral point of view insofar as the right to vote usually requires being of legal or majority age. It can also play a role in systems where polling stations are made up of citizens designated by the drawing of lots, forming a compulsory civic duty from which those above a certain age can be exempted.
Along with these particulars that might be considered essential, some systems add others that are accessory but that may be important in the establishment of an adequate electoral register. Among them, are the following:
The number of the national identity document or card. This information is recorded in countries where they exist, or the social security number or the passport in countries that, due to cultural reasons or economic development, do not have such official national identification documents (e.g., Great Britain and the United States).
The reason for its inclusion is its usefulness as a control digit, to avoid
that the inevitable coincidences in names existing on all registers lead to
registration duplications.
This is an important correction mechanism of the registers, which is why universally there is a tendency to include it, either by means of an overall identity card issuing process, or because certain documents (such as the Social Security card in the United States) are progressively assuming the functions of the national identity card. For traditional reasons of privacy, only Great Britain seems to continue opposing the very existence of a compulsory national identity document.
Nationality. This information can be relevant in countries that permit foreign residents to vote in some types of elections, in particular in the municipal and European Parliament elections, but that exclude the right to participation in the presidential or parliamentary elections.
Education level. Although presently this is mostly an irrelevant detail, and where it is maintained, it is more a remnant of the restricted voting system in which it was used, it still fulfills some purpose in the systems where appointments to polling stations are made up of citizens who surpass certain educational levels. However, even in such cases, only this information should be indicated, without any further unnecessary particulars.
Political party membership. In the majority of the countries, this detail is unthinkable on a public register, to the extent that it will probably be considered unconstitutional in many democratic states that hold it is a citizen's right not to make any public declarations on their political ideas or beliefs. However, in the United States it is introduced, normally voluntarily, as a consequence of the system of primary elections, characteristic of that system, so that to the two big parties, the register also serves as a roll of their more dedicated supporters.
Race. This information may be applicable in systems that consider it relevant to the setting of ethnic electoral constituencies and reserves. Apart from such cases, this is an element that should not appear on electoral registers, and when it does, it should be for motives that have nothing to do with the elections, such as the forming of juries in the United States.
Gender. This is a factor which serves no electoral purpose in modern democracies, so its existence in some systems has to be attributed to its heritage of prior restricted vote, or because of its utilisation in the same non-electoral sense as race.
