In India, the Constitution provides for universal adult suffrage. Citizens aged 18 years or above subject to certain other eligibility conditions can get their names included in the electoral list.
However, there is no system of automatic inclusion of citizens in electoral list once they turn 18.
I want to know whether there are any countries (prominent democracies) which have the system of automatic registration of citizens in their electoral rolls.
According to Wikipedia, some countries that do register citizens for voting without them having to explicitly ask for it are:
Commenters also pointed out these additional examples:
Usually voter registration is tied to residency registration. When one is registered as a resident, they get automatically added to the voters roll as soon as they reach the required age. This of course requires that the country has and enforces mandatory residency registration.
Since all residents must register with the municipal authorities, they know which residents are citizens. Before each election, one gets a postcard with a notification about the date and the place of one's polling station, plus instructions how to request absentee ballots.
There are some scenarios like citizens living abroad where special forms would be necessary.
Intuitively, countries where voting is mandatory would be likely to automatically register eligible citizens. This turns out to be true for Belgium.
According to the official Federal Office of Elections website,
Les Belges inscrits dans les registres de la population d'une commune belge ne doivent pas s'inscrire pour les élections. Ils sont automatiquement inscrits sur la liste des électeurs.
My translation: Belgians that are registered on the population register of a Belgian municipality don't have to register for elections. They are automatically registered on the voters list.
No mandatory voting but eligible French voters are automatically registered as well (provided they participated in the citizen census at the age of 16). From the official website of French administration:
Chaque Français qui devient majeur est inscrit automatiquement sur les listes électorales, à condition qu'il ait effectué les démarches de recensement citoyen au moment de ses 16 ans. Si l'inscription d'office n'a pas pu avoir lieu (recensement tardif, déménagement après le recensement, ...), il doit demander à être inscrit sur les listes électorales auprès de sa mairie.
My translation: Each French citizen who becomes an adult [age 18] is automatically registered on the electoral lists, provided that he has completed the citizen census procedures by the time he turns 16. If the automatic registration could not take place (late census, moving after the census, ...), he must request to be registered on the electoral lists with his town hall.
According to the Brennan Center, 16 states (plus the District of Columbia) currently or will soon automatically register citizens to vote (on an opt-out basis) when they interact with government agencies, generally the Department of Motor Vehicles (DMV) where people register their cars and get and renew driver’s licenses (which are the main form of ID in the US).
First, AVR makes voter registration “opt-out” instead of “opt-in”—eligible citizens who interact with government agencies are registered to vote or have their existing registration information updated, unless they affirmatively decline. Again, the voter can opt-out; it is not compulsory registration. Second, those agencies transfer voter registration information electronically to election officials instead of using paper registration forms. These common-sense reforms increase registration rates, clean up the voter rolls, and save states money.
Like most things in the US, the details vary from state to state, but these programs do seem to have significantly increased voter registration rates:
The results have been exciting. Since Oregon became the first state in the nation to implement AVR in 2016, the Beaver State has seen registration rates quadruple at DMV offices. In the first six months after AVR was implemented in Vermont on New Year’s Day 2017, registration rates jumped 62 percent when compared to the first half of 2016.
