Anecdotal evidence from several leaks, including the “Panama Papers” and “Paradise Papers”, highlighted the role of certain intermediaries in actively assisting their clients in reducing their respective tax burdens. Although some complex transactions are entirely based on legitimate motives, others appear to be driven by the singular desire to avoid tax obligations at home. This is why in May 2018, the European Commission enacted the Council Directive 2018/288/EU (or DAC6) mandating the reporting of aggressive tax planning arrangements. Thanks to DAC6, tax authorities will get timely access to a comprehensive set of information on currently used tax planning arrangements. Still, the authors’ cross-country analysis highlights that a higher level of standardization of local DAC6 laws should be achieved to ensure the collection of high-quality, actionable data. Overall, this study offers valuable recommendations to countries around the world on the design of laws requiring the reporting of aggressive tax planning arrangements.