How is the national electoral register created?

Compilation of Voter Lists

Taiwanhas a comprehensive household registration system. Compilation of voter listsis the statutory duty of government agents. With the exception of citizensresiding overseas during the Presidential and Vice Presidential election,citizens do not have to register to vote. Unless incompetence has been declared,citizens, aged 20 or above, who have resided in their respective constituenciesfor a stipulated period, are entitled to vote. Their records are automaticallyfiled by Household Registration Officers at least 20 days prior to the ElectionDay. There are approximately eighteen million voters throughout the country,which is around three fourths of the population.

Source:http://engweb.cec.gov.tw/files/11-1030-4276.php