The deduction of interest expenses for corporate tax purposes has attracted the attention of tax policymakers and multinational enterprises owing to concerns about base erosion and profit shifting. Prior to the transposition by Member States of the Anti-Tax Avoidance Directive that established a minimum standard, national rules to limit the tax deduction of interest expenses and anti-abuse rules to tackle perceived aggressive tax planning lacked uniformity and consistency at EU level. This resulted in legal disputes, especially in cross-border intra-group financing cases when transfer pricing based on the arm’s length principle is also applied. The Court of Justice of the European Union has set general guidelines and an interpretative framework. However, the opinion of the Advocate General in the X BV case (C-585/22), suggesting a departure from the Lexel case (C-484/19), raises significant concerns. In the authors’ opinion, this approach could lead to an overreaching application of the GAAR even to arrangements subject to the arm’s length principle that, based on economic rationality and substance, is intended to treat in the same way cross-border intra-group and third-party structures and transactions.