Spain joined the European Union in 1986 and was in the first-wave countries to adopt the euro on 1 January 1999.tatus: Euro-area member since 1 January 1999. Fixed conversion rate : €1 = 166.386 ESP. Adoption of the euro: The euro banknotes and coins were introduced in Spain on 1 January 2002, after a transitional period of three years when the euro was the official currency but only existed as 'book money'.