That's interesting. The only two countries who have a formal opt out on the Euro are the UK & Denmark, with Sweden a de facto default by not joining ERM II. Everyone else who joined the EU later didn't get the choice, so Hungary formally signed up to the Euro too. Not saying they're likely to switch to the Euro soon, but I don't see how they can now pass a law that confirms the Forint as the only national currency forever, when they are already signed up to the EMU (on the long term).