In this chapter, Roman Seer and Sascha Kargitta describe the different types of tax information exchange, their respective advantages and disadvantages and the underlying legal principles. The chapter focuses on the bilateral information exchange clauses in double tax treaties as provided for by Article 26 OECD Model Tax Agreement and the OECD Model Tax Information Exchange Agreement. There is also an examination of multilateral approaches such as the Convention on Mutual Administrative Assistance in Tax Matters. The authors examine the EU efforts to expand automatic exchange of information, largely modelled after the US FATCA, through the 2011 Directive on Administrative Cooperation and its various subsequent amendments (such as in order to include the automatic exchange of advance crossborder rulings and advance pricing agreements, the implementation of country by country reporting and reporting of aggressive tax planning). The authors analyse legal concerns derived from the evolving tax information exchange system, in particular the possible violation of universally existing data protection provisions. While the authors acknowledge the need for effective information exchange, they argue that the use of exchanged information by the participating tax authorities may, at times, go beyond what is necessary. In particular, they point to the risk of the information exchanged not being processed properly, but instead being piled up in administrative IT systems that may amount to unconstitutional ‘data cemeteries’.