This article critically studies case law on beneficial ownership in Spain, Switzerland, England, Canada and France to conclude that what seems to be the prevailing opinion (economic/substance-over-form analysis) of that term is not the one that best conforms the object and purpose of tax treaties. The minority opinion, represented by the Canadian Prévost judgements, is given attention as the most promising way to avoid some of the problems of the concept of beneficial ownership. Recent initiatives of international organizations (OECD, UN) affecting the concept of beneficial ownership are also considered to study other relevant issues in connection with beneficial ownership (liability of withholding agents when it is found that the person receiving income is not the beneficial owner, extension of the concept to other treaty articles) where clarification is needed.