This note examines the Court of Justice of the European Union decision in F S.A. v. Director of the National Treasury Information Bureau (Case C-18/23), which dealt with the issue of non-resident internally managed collective investment undertakings (CIUs) attempting to be treated as comparable to resident externally managed CIUs, and their equal tax treatment under the national law of an EU Member State, based on the free movement of capital. The Court established, first, that resident and non-resident CIUs are in a comparable situation; second, that protection of investors may be considered an unwritten potential justification that restricts the free movement of capital; and third, that, in the case at hand, such a potential unwritten justification was not appropriate to achieving the stated aim of protecting investors. The findings resulted in a need for equal tax treatment to be afforded to non-resident internally managed CIUs by EU Member States that currently only provide for tax exemptions to externally managed CIUs.