This book contains articles prepared by many of the speakers of IOTA’s 21st General Assembly which took place in Kyiv, on 28-30 June 2017. The Assembly addressed the changes in the economy driven by technology and multiplication of new and innovative business models. Speakers of the Assembly focused on how this trend is causing both challenges and opportunities for tax administrations to re-invent themselves in order to keep pace with the present and anticipate the future. The articles of speakers in this book include not only what they have presented but their further thoughts on the subject as well.