You live Portugal and receive pension from Finland
If you live in Portugal and receive a pension from a payor in Finland, you must pay tax to Finland.
If you are paying tax on your pension to Portugal, too, contact the Portuguese tax authorities to ask for the double taxation to be eliminated for the part of your income consisting of pensions received from Finland. Taxes you have paid to Portugal on your Finnish pensions do not affect your tax assessment in Finland.
Changes concerning Portugal’s and Finland’s taxation as of 2019
Starting 2019, those who live in Portugal pay tax to Finland on their pensions received from payors in Finland.
In the previous tax treaty between Finland and Portugal (signed in 1970) there were provisions on the avoidance of double taxation with regard to residents’ income, also including pensions. However, Finland issued a notice of termination of the treaty, and from 31 December 2018 on, the treaty is no longer applicable. A new treaty signed in 2016 was accepted in Finland, but was never accepted by the Portuguese tax authorities. Accordingly, no treaty is in force and no provisions have gone into effect between Finland and Portugal, which would have an impact on pensions.
Read more about how income taxes are imposed on pensions sourced to Finland: “Taxation of pensions in cross-border circumstances” – Eläketulojen verotus kansainvälisissä tilanteissa (available in Finnish and Swedish, link to Finnish), section 6.3 The taxation process in Finland - 6.3.4 concerning Portugal.