The Ministry of Finance announced today the deadlines for filing the 2012 Income Tax Returns and the 2012 E9 forms for real property (Circular Pol. 1055/29-2-2012).
Income Tax Returns of:
- Partnerships, Joint-ventures, Non-profit orgnaizations: until 30 April 2012
- Societes Anonymes and Limited Liability Companies: until 10 may 2012
- Individuals: until 15 June 2012. 
The E9 forms for 2012 are to be filed until 31 July 2012.

Source: Ministry of Finance (announcement in Greek)

On 22 February 2012 the OECD announced that Greece has signed the Convention on Mutual Administrative Assistance in Tax Matters, a multilateral agreement that was developed jointly by the Council of Europe and the OECD and that is open for signature to all countries. The Convention promotes international co-operation in the assessment and collection of taxes.
Signatories to the Convention are so far:  Argentina, Australia, Belgium, Brazil, Canada, Denmark, Finland, France, Georgia, Germany, Greece, Iceland, India, Indonesia, Ireland, Italy, Japan, Korea, Mexico, Moldova, Netherlands, Norway, Poland, Portugal, the Russian Federation, Slovenia, South Africa, Spain, Sweden, Turkey, Ukraine, the United Kingdom and the United States.
Source: OECD

After receiving a number of complaints by taxpayers who found themselves charged with an amount of notional income on which tax was calculated and due, the Greek Ombudsman published a report in which it concluded that the Greek Tax Administration does not provide adequate information to taxpayers on how to challenge notional income rules.

The Ministry of Finance issued a circular providing guidance regarding the application of the provisions on the Energy Performance Certificate that is now required to be issued for all leased real property in Greece. 
According to Circular No. 1018/13-1-2012, the Energy Performance Certificate of any building larger than 50 square meters that is leased, wholly or partially, for the first time. The Certificate is required by the Tax Offices in order to proceed with the registration of the lease agreement. Any lease agreement that is taken to the tax office after the 9th of January 2012 must be accompanied by the Energy Certificate (if it is a new lease agreement and not the renewal of an existing one).  
The Certificate is issued by certified energy inspectors; a list of the certified inspectors is to be found at a special site of the Ministry of Environment, Energy and Climate Change at www.buildingcert.gr.

You can find the list of the VAT rates that apply in the EU Member States as in force on 1 January 2012 on the website of Taxation and Customs union Directorate of the European Commission.