A person aged 18 or over may be naturalised as a Portuguese citizen after 6 years legal residence. There is a requirement to have "sufficient knowledge" of the Portuguese language and "effective links to the national community". Children aged under 18 may acquire Portuguese citizenship by declaration when a parent is naturalised, and future children of such Portuguese nationals will be considered Portuguese citizens by birth. A naturalised Portuguese citizen only starts to be considered Portuguese once the naturalisation process is done. Therefore, nationality acquired through naturalisation "is not" transmitted to any possible descendants "already" adult by the time their parents' naturalisation process is finished.