Residents of Greece are taxed on their worldwide income, subject to certain treaty exceptions, although citizens of most countries are exempt from paying taxes in their home country when they spend a minimum period abroad, for example, one year.
As with many countries the Government has doubled taxation treaties including Argentina, Austria, Belgium, Canada, Cyprus, Czech Republic, Denmark, Egypt, Finland, France, Germany, Hungry, Iceland, Ireland, Italy, the Republic of Korea, Luxembourg, the Netherlands, Norway, Poland, Romania, the Slovak Republic, Sweden, Switzerland the United Kingdom, and finally the United States of America.
If one is not residing in Greece although owns assets it is, by law, that all owned be filed with the Greek Inland Revenue and all the necessary assets must obtain a tax return and a listing of all monies earned.
If one is planning to reside in Greece then you should notify the Inland Revenue in your present country. You may be entitled to a tax refund if you depart before the end of the tax year.
When living in Greece and in full time employment by law you are liable to pay income tax, the same procedure is carried out when starting your own business.