Judgment of the Court (Fifth Chamber) of 12 March 2026 (request for a preliminary ruling from the Tribunal de première instance du Luxembourg – Belgium) – BX v État belge

(Case C-150/25,  (1) Marhaux  (2) )

(Reference for a preliminary ruling - Article 45 TFEU - Freedom of movement for workers - Income tax - Employment income received in another Member State - Exemption with progression in the Member State of residence - Failure to apply a bilateral convention for the avoidance of double taxation by a contracting State - Loss of part of the tax advantages relating to the personal and family circumstances of the taxpayer)

(C/2026/2692)

Language of the case: French

Referring court

Tribunal de première instance du Luxembourg

Parties to the main proceedings

Applicant: BX

Defendant: État belge

Operative part of the judgment

Article 45 TFEU

must be interpreted as precluding national legislation the application of which leads to the loss in part of the benefit of a tax deduction designed to take account of the personal and family circumstances of resident taxpayers in one Member State, where they receive employment income in a second Member State, which is exempt from tax in the Member State of residence under a bilateral tax convention, whereas resident taxpayers who have no income from another Member State wholly benefit from that deduction, where, under that bilateral tax convention, the loss of that part of that deduction should have been offset, in the second Member State, by the corresponding opportunity to obtain a similar deduction, in proportion to the income received in the second Member State, but that that was not the case based on the application of that convention in the second Member State, provided that there is no overriding reason in the public interest capable of justifying such a loss.

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(1)  OJ C, C/2025/3029.

(2)  The name of the present case is a fictitious name. It does not correspond to the real name of any party to the proceedings.