This article analyses the principal updates in tax cooperation and international tax exchange of information, which constitute enforcement mechanisms to EU tax cooperation. The article also analyses the new EU Directive 2011/16/UE of tax cooperation, which is meant to open a new era in EU tax cooperation and introduces some relevant new norms in relation to the validity of the proofs and documents obtained from abroad. Nevertheless, the international tax exchange of information present several limits which affect different aspects of the proof activity in the internal EU member states between tax Administration and the taxpayers. This article analyses some of these aspects which appear in some decisions of the EU Court of Justice.