This book explores tax arbitrage opportunities resulting from financial engineering techniques with cross-border financial instruments such as hybrids, synthetics, and non-traditional financial instruments. Firstly the author clarifies the concept of three kinds of complex financial instruments, and thereafter he discusses the most adequate tax treatment of these instruments in cross-border situations. For this purpose he identifies economic substance as an objective benchmark for the taxation of financial instruments to achieve greater international tax neutrality, and examines the role of the expected return taxation theory. The book also contains a comparative analysis of relevant developments in a number of jurisdictions, including Australia, Belgium, Brazil, Luxembourg, Portugal, UK and USA.