"The premises in which the voting station (s) should be established abroad shall be defined ninety days prior to the election or plebiscite, by a resolution from the Electoral Service. There must first be a report from the Directorate General of Consular Affairs and Immigration of the Ministry of Foreign Affairs. Polling places should preferably be located in the same consulates and meet conditions of easy access." Source
Constitution 1980 (last amended in 2015)
The citizens who are eligible to vote and that are residing abroad, may vote from abroad in the presidential primary elections, in the elections of President of the Republic, and in national plebiscites.
A constitutional organic law shall establish the procedure to materialize the registration in the electoral register and will regulate the way in which the electoral and plebiscitary procedures shall take place abroad, in conformity with what is established in the first and second paragraphs of article 18.
See also the following reports: