Euro zone is a monetary union of the 19 member states where despite each member having their own country currency and government as well as central bank, the monetary union decided to come together to adopt Euro as primary currency to trade with each other. The fiscal harmonization is important for all the Euro member states because despite Euro being the primary currency to deal with each other within each country many countries still use their own currency and if one government fiscal expenditure is not matched by its revenue then it will borrow money from other member states and that will increase its debt. Increasing debt beyond a point will create a significant problem for the repayment of the debt because you can not consistently increase your debt without increasing your income as we saw in Greece, where the government expenditure was consistently exceeding its revenue until it reached a point where they would default on its obligation. If one member state fiscal expenditure is too much and it is defaulting on its payment then either other members will have to bail him out or the basic structure of monetary union will probably not be able to sustain in the long run in such state because every member state would go and spend beyond its income because it knows that it would be bailed by some other members so fiscal harmonization for each members is very important in order to make sure that the monetary union and its broader objective of Euro as a primary currency is achieved.