Purpose This paper aims to explore the intricate and controversial sale of six hydroelectric dams in the Douro hydrographic basin by Energias de Portugal (EDP), a prominent Portuguese energy company, to a French Consortium – ENGIE. The transaction, completed at the end of 2020, has sparked significant debate and scrutiny within the Portuguese legal and fiscal spheres due to its corporate and budgetary manoeuvres. The crux of the controversy lies in the complex corporate restructuring strategies used by EDP and the acquiring consortium to execute this transaction. These strategies, aimed at achieving tax neutrality, effectively circumvented the traditional tax liabilities typically associated with large-scale asset transfers. The paper delves into the legal intricacies of this operation, scrutinising the application of taxes such as stamp duty, corporate income tax, value added tax and property transfer tax, which were, in theory, applicable to the transaction. Furthermore, this study examines the broader implications of the deal, particularly concerning the principle of tax neutrality in corporate restructurings, the enforcement of anti-abuse clauses and the economic substance over legal form doctrine. Design/methodology/approach This study is based on secondary data supported by publicly reported evidence. Findings This case study highlights the challenges in taxing corporate transactions in the modern financial landscape and reflects these corporate manoeuvres' societal and ethical considerations. Originality/value Through an analysis of legal frameworks, corporate strategies and tax policies, this paper provides a comprehensive understanding of the transaction and its implications, offering insights valuable to legal professionals, policymakers and scholars in corporate law, taxation and business ethics.