Annual return has been due on 20th of May 2015 (for non-residents registered for VAT in Greece) and on 30th of April 2015 (for residents registered for VAT in Greece).
Greece extended deadline for annual returns to be submitted
By the decision of the government deadlines have been moved to 20th of September 2015.
Please be aware that this year is the last year where annual return will have to be submitted.