EU nationals who have recently obtained new residents permits say the system has changed. The new certificate (veveosi eggrafis) does not expire. Athens News published the following information on 30th January 2009.
GREEK TAX NUMBER
You cannot do much, if you live in Greece, without having a tax number. If you have a tax number then you may be required to make an annual tax declaration, even if you earned nothing in Greece. You have to make an annual declaration if you own a house, a car or certain other, so called, luxury possessions, in Greece. If you do not make the declaration then you will be fined. The tax office will not attempt to contact you, to tell you that you must make a return. You will be penalised when you want to do something that requires a tax clearance certificate. This may be selling a car or house or land or setting up a business etc.