Once a person’s eligibility to cast an external vote is established, there is usually a second requirement to be met—the need to be registered on the electoral register in order to show that he or she is entitled to vote. Special registration requirements may be necessary for external electors, or they may be required to register in the same way as all other electors. Registration requirements thus introduce a second stage into the entitlement process and may serve to limit the numbers of persons who are eligible to cast an external vote.

In most countries ordinary electors are registered in respect of particular locations— usually their home residence—so that they can establish their right to vote in particular electoral districts and for regional levels of government. As it may be difficult or impossible to allocate an external elector to a particular locality in the home country, it is sometimes desirable to use a special registration process for external electors.

Where the eligibility requirements and/or voting rights for external electors are different from those for in-country electors, it is essential that external electors use a separate registration process. For example, where they are entitled to vote for national elections but not local elections, the electoral register must clearly distinguish external electors.

Whether external electors are listed on a special external electoral register or are listed on the normal electoral register will depend on local circumstances. One relevant factor would be whether a country has one national electoral register or different registers for different levels of government. Another would be the level of technical sophistication of the electoral register. Australia, for example, essentially maintains one computerized national electoral register that is used for elections for all levels of government. While it has a separate registration form for external electors, their names are stored on the national electoral register with all other registered electors, with an annotation indicating that they have registered as external electors. Other countries, particularly those that have different electoral registers for different regions and/or levels of government, might be more likely to maintain separate electoral registers for external electors. Where electoral registers are kept by different authorities for different levels of government or for different regions, such as the different states in the USA, the process for registration as an external elector may vary from jurisdiction to jurisdiction and/or from place to place.

In some cases, simple registration on the normal electoral register is sufficient for an external elector to retain the right to vote, without the need for special registration as an external elector. For example, Swedish residents living abroad remain on the electoral register for an absence of up to ten years. Only those who are absent for longer than ten years need to register in order to remain on the electoral register.

People who are absent for short periods, such as those who are on holiday, generally do not need to apply for special external elector status if they are listed on the normal electoral register.

Where a person is absent for a longer period, many countries require special registration as an external elector. This is particularly important where the electoral register is regularly reviewed, and people are removed from it if they do not appear to be resident at their registered address.

Registration as an external elector usually requires the elector to complete a form, which is then processed by the authority responsible for keeping the electoral register. In some cases, the person may be required to provide documentary proof of eligibility, such as proof of citizenship, age or residence. When considering whether such evidence should be required, attention should be given to the feasibility of this requirement. If a person is applying for registration from outside the home country, the requirement that identity documents (IDs) be provided may be impractical or unreasonable. Where a country is in transition or is otherwise subject to civil instability, many citizens, particularly refugees, may not have valid IDs (see chapter 7 and the case studies on Afghanistan, Bosnia and Herzegovina, and Iraq). In these cases, the registration process may need to rely on a declaration signed by the applicant and/or a declaration signed by a witness.

In most cases it would be appropriate to apply the same level of authentication requirements to registration as an external elector as apply to the normal electoal registration process.

Where a specific external elector registration form is required, care should be taken to ensure that the form seeks sufficient information to demonstrate that the applicant is entitled to be registered. A registration form could for example require the applicant to state how they acquired citizenship, when they last lived in the home country, whether and when they intend to return to the home country (if relevant) and when they were born.

Keeping a register of external electors up to date is a difficult task. Electoral registration authorities are unlikely be able to review the status of registered external electors who are resident abroad. In practice, the most feasible approach is to rely on external electors to update their details when applying to register or when actually voting. One way to keep the electoral register free of out-of-date entries is to remove the names of those who do not vote, for example, for one or two national elections in a row.