The revised legislation, which is among the most favourable of Western countries in terms of acquiring citizenship, came into force last Friday.
These alterations have resulted in foreign children who have lived here for two years now being considered Portuguese - unless they declare they do not want Portuguese nationality.
However, these children would still have to follow the standard procedure of registering as Portuguese citizens before being handed their Citizen’s Card or Portuguese passport.
The legislation, which has now undergone its eighth legislative reform since being introduced in 1981, also says that foreigners who have lived in Portugal for five years can also apply for Portuguese nationality.
Foreign children who are born in Portugal will also qualify for citizenship. The only requirements are that one of the parents has been living in Portugal for at least five years, (even if they have done so illegally) and that the child has completed either primary or secondary schooling in the country.
Another alteration will see parents now allowed to acquire Portuguese nationality via their children. Once more, they will need to provide proof that they have resided in Portugal for at least five years, but are not required to have done so legally.
However, any applicant who has been sentenced to three years imprisonment will not be able to acquire citizenship, while residents from Portuguese-speaking countries will no longer be required to complete a language proficiency test.
This comes as the Organisation for Economic Cooperation and Development (OECD) announced that the number of foreign residents arriving in Portugal has climbed to its highest figure since 2010.
Latest available figures reveal that 47,000 foreigners arrived in Portugal in 2016, which is up by 24 percent in relation to the previous year.
According to the OECD, just under 400,000 foreigners resided in Portugal in 2016.
The organisation further explained that more than half the increase in foreign residents is due to the arrival of EU nationals, which has soared 40 percent in the space of just two years.
France was responsible for the most arrivals in 2016 from within in the EU, followed by Italy and the United Kingdom, which the OECD says is largely the result of Portugal’s favourable tax regime for non-habitual residents.
The OECD meanwhile also revealed that 29,000 foreigners were granted Portuguese citizenship in 2016, which is up by more than 30 percent on 2015.