If you have over €10,000, or the equivalent sum in other currency, when entering or leaving the EU, you must declare the cash to Customs.
Cash means:
Credit and debit cards are not considere ...
Declare your cash by filling out a form.
Submit the cash declaration form to Customs upon your arrival or departure. Print and fill out the cash declaration form in advance. Attach a copy of your passport or identity document.
After arriving, choose the red channel or declare your cash to Customs in another manner.
Regulation (EU) 2018/1672 of the European Parliament and of the Council of 23 October 2018 on controls on cash entering or leaving the Union and repealing Regulation (EC) No 1889/2005 (europa.eu)
Laki Euroopan unioniin saapuvien tai sieltä poistuvien käteisvarojen valvonnasta 432/2021(Finlex)