The Maastricht Treaty laid down certain conditions (the convergence criteria) to be satisfied before Member States could participate in EMU. The Treaty does provide for some flexibility in the interpretation of specific criteria.

The convergence criteria laid down in the Maastricht Treaty are as follows:

• The rate of inflation should not be more than 1,5 percentage points above the average of the three best-performing Member States.
• Long-term interest rates should not be more than 2 percentage points above the average of the three Member States with the lowest inflation rates in the Union.
• The budget deficit should not be greater than 3% of Gross Domestic Product (GDP).
• Public debt should not exceed 60% of GDP or should be making 'satisfactory progress' towards achieving the reference rate.
• The national currency should be within the normal fluctuation margins of the Exchange Rate Mechanism (ERM), without severe tensions, for a period of at least two years.