The ATR is a customs document used in international trade between the EU and Turkey in order to reduce the duty rates. It is based on the customs union between the Turkey and European Union. Some product categories like agricultural products, steel or coal are not included in this customs union and thus do not take advantage from the preferential agreement but they might be included in the EU-Turkey FTA agreement. The document is prepared by the shipper and certified by the custom authorities at the country were the products will beloaded from. Many times the sellers authorize a customs agent to do this type of paperwork. This is a good and safe choice for a companies that are beginners in the export field and do not have the know how and experience to deal with the custom procedures.
To be noted that the ATR is not considered to be the substitute of the Certificate of Origin. Due to this in some occasions some customs in Turkey might ask for both the ATR and the Certificate of Origin (especially when the products arrive in Turkey by the sea). The ATR certifies that the products have put in duty free circulation between the EU and Turkey.
Below you may find two example of an ATR document one written in. English and one written in Greek: