Launched in 2005 after decades of seeking the formal start of an EU membership bid, the negotiations dovetailed with Erdoğan's first economic reforms after he took power in 2003.
However, Germany and France were sceptical about absorbing a large, mainly Muslim nation.
The European Commision, the EU executive, is expected to come forward with a report early next year on whether EU governments should annul the membership talks with Turkey.
Aside from money that the EU gives Turkey for taking in Syrian refugees, Ankara is set to receive 4.4 billion euros between 2014 and 2020, but only a small part of that has been committed for projects such as infrastructure.
Some of the funds could go to finance the 2016 migration deal with Turkey, under which the European Union is set to pay another 3 billion euros by the end of 2018, diplomats said.
