Comment expliquer l’hétérogénéité des performances susceptible d’exister entre des entreprises concurrentes ? Telle est, selon Rumelt, Schendel et Teece (1994), l’une des questions structurante de la littérature stratégique. Au-delà des approches traditionnelles fondées, en particulier, sur les ressources et les compétences ou sur le positionnement stratégique de la firme, certains travaux ont étudié les implications, en termes de performances, des stratégies fonctionnelles. Toutefois, dans cette perspective, la contribution des stratégies fiscales des entreprises demeure une question peu étudiée. Aussi la présente thèse s’attache-t-elle à déterminer dans quelle mesure et selon quelles modalités la stratégie fiscale est susceptible d’influer sur les performances de la firme – donc de contribuer à lui conférer un avantage concurrentiel. À cet effet, celle-ci s’appuie sur une exploration hybride mobilisant des témoignages de praticiens de la fiscalité, des documents d’entreprise, la littérature professionnelle, des travaux de sociétés d’audit et de conseil, des rapports d’institutions publiques, ainsi qu’une étude approfondie de la littérature en sciences de gestion et en économie relative aux pratiques fiscales des firmes. / How to explain differences in performance among competitors? According to Rumelt, Schendel, and Teece (1994), this is one of the key questions of the literature in strategic management. Beyond traditional approaches based on resources and competencies or on strategic position of the firm, some studies have examined the implications of functional strategies in terms of performance. Nevertheless, from this point of view, there is little research on the contribution of corporate tax strategies. Therefore, this thesis aims to determine the extent to which the tax strategy can influence the performance of the firm and how. It thus seeks to assess how the tax strategy can contribute to provide a competitive advantage to the firm. The thesis is based on a hybrid exploration mobilizing tax practitioners’ experiences, corporate documents, professional literature, work of auditing and consultancy companies, reports of public institutions, and a comprehensive study of literature in management and economics relative to firms’ tax behavior. First, this thesis aims to “contextualize” firms’ tax strategies. Special attention is devoted to corporates’ tax planning; because of its specific nature, it makes the various aspects of firms’ tax behavior, of their environment, and their respective developments more easily visible. Thus, it is shown that the “tax lever” is in position to substantially influence the performance of companies, with the help of current economic developments, which increase tax opportunities. However, these evolutions expose organizations to magnified and increased risks. Second, on the basis of these different analyses, this thesis aims to explore the conditions in which it is possible for a firm to improve its performance over the long term through taxation. Consequently, it examines conditions of the formulation of tax strategy and its implementation through the study of tax function management, tax risk management, and determinants of “tax investment” — which provide a measurement of possible effects of tax strategies on competition between firms.