The finance ministers of around 50 countries meet in Berlin on Wednesday to sign a deal they hope will put an end to banking secrecy.
The forum, set up under the auspices of the Paris-based Organisation for Economic Cooperation and Development (OECD) and the European Union, brings together representatives of more than 120 countries.
The finance ministers are scheduled to sign on Wednesday a Multilateral Competent Authority Agreement, which will designate which institution in each country is responsible for transferring tax data to other member states.
An international movement to end banking secrecy has gathered momentum in recent years, particularly following the enactment in the United States of its 2010 Foreign Account Tax Compliance Act or FATCA.
GATCA is expected to be up and running in 2018.