As long as registered in the census in the national territory, all the Portuguese and the citizens of the following countries can vote in the elections of the in the elections of local authority bodies:
For that, it is necessary that they fulfil one of these conditions:
In the elections to the European Parliament, the citizens of the European Union, who are not nationals of the Portuguese State, but are registered in Portugal, can choose to elect the deputies of their country or the Portuguese deputies.
In the elections for the Assembly of the Republic and Legislative Assemblies of the Autonomous Regions, Brazilian citizens holders of the Statute of Equality of Political Rights (Treaty of Friendship, Cooperation and Consultation between the Portuguese Republic and the Federative Republic of the Brazil, signed in Porto Seguro on April 22, 2000) are able to vote.
In general, the registration of foreigners is permitted by the statutes of political parties with parliamentary representation, as long as they have political rights in Portugal.
To register, you must go to the voter registration commission (Comissão Recenseadora), at the parish council corresponding to the address indicated in the valid residence permit. The period is continuous, being suspended only from the 60th day prior to each election until it is held.
Source: High Commission for Migration (ACM)