How is the national electoral register created?

San Marino, OSCE/ODIHR NEEDS ASSESSMENT MISSION REPORT, ‘EARLY PARLIAMENTARY ELECTIONS 20 November 2016’, VOTER REGISTRATION AND IDENTIFICATION, PP-6, accessed 16 November 2018

Voter registration is passive and voter lists are based on information extracted from the permanent electronic population register. Voter lists are updated on a yearly basis by 31 January. Updated lists are displayed for public scrutiny in polling stations and in diplomatic and consular offices abroad until 28 February.