Among other criteria , member countries must not allow annual budget deficits to exceed 3 % of gross domestic product , and public debt must be under 60 % . The Treaty of Maastricht which enabled the euro 's creation was signed in 1992 . It is a treaty that has been ratified by all EU countries, but it does not have legal force as such and can be changed or ignored at any time without changing its meaning. It is used over the eurozone 's 17 countries . But it is under pressure due to the eurozone 's debt crisis .
The Treaty of Maastricht which enabled the euro 's creation was signed in 1992 . It is a treaty that has been ratified by all EU countries, but it does not have legal force as such and can be changed or ignored at any time without changing its meaning. It is used over the eurozone 's 17 countries . But it is under pressure due to the eurozone 's debt crisis .