Facts
In a judgment of 21 April 2026 (No. 52991C), the Higher Administrative Court (Cour administrative) dismissed an appeal brought by a Luxembourg société à responsabilité limitée (the “Company”) acting through its liquidator. The Company held a 49.95% stake in a Polish entity (the “Polish Entity”) comparable to a Luxembourg société en commandite simple. The Polish Entity was fiscally transparent under Polish and Luxembourg law and therefore disregarded for tax purposes. As a result, its entire assets and liabilities were deemed directly attributable to, and taxable in the hands of, the Company, including real property under construction in Poland financed by bank debt (the "Immovable Property"). For the financial years 2013 and 2014, the Company included those elements in its unitary value (valeur unitaire) for Luxembourg net wealth tax (impôt sur la fortune, "NWT”) purposes. However, the tax authorities excluded both the asset and the related liability from the Company’s NWT basis by virtue of the Luxembourg-Poland double tax treaty (the “Lux-Poland DTT”), a position upheld by the Lower Administrative Court (Tribunal administratif) on 30 April 2025 and confirmed on appeal.
Higher Administrative Court's reasoning
Domestic law and Tax Treaty framework
As a Luxembourg-resident capital company, the Company was subject to unlimited NWT on its worldwide fortune under the Vermögenssteuergesetz ("VStG") of 16 October 1934. Under Luxembourg domestic law, this includes assets held through fiscally transparent entities wherever located. The unitary value is determined under the Bewertungsgesetz ("BewG") of 16 October 1934, which excludes treaty-exempt assets from the taxable base (§§ 59 and 73 BewG). Under Articles 6(2) and 23(1) of the Lux-Poland DTT, Polish real estate is taxable exclusively in Poland and therefore exempt from Luxembourg NWT. As the Lux-Poland DTT is silent on debt-deductibility (as is the OECD Commentary on Article 22 of the OECD Model Tax Convention), Luxembourg domestic law fills the gap: §§ 62 and 74 BewG render non-deductible any debt economically linked to an exempt asset from NWT. The Higher Administrative Court confirmed the exclusion of both the Immovable Property and the financing debt.
Non-aggravation principle under the double tax treaty
The Company invoked the non-aggravation principle, relying on the Higher Administrative Court's prior judgment No. 19407C of 10 August 2005, under which a double tax treaty cannot worsen a taxpayer's domestic position. The Higher Administrative Court distinguished that case: in 2005, the double tax treaty risked blocking a deduction that domestic law would otherwise have permitted. Here, the non-deductibility of the financing debt flows directly from Luxembourg domestic law (§§ 62 and 74 BewG) as an automatic corollary of the asset's exemption - not from any prohibition in the DTT. The non-aggravation principle was therefore inapplicable.
Conformity with EU law - freedom of establishment
The Company argued that the combined effect of Luxembourg law and the Lux-Poland DTT breached the freedom of establishment (Article 49 of the Treaty on the Functioning of the European Union ("TFEU")) or, alternatively, the free movement of capital (Articles 63-66 TFEU). The Court held that Article 49 TFEU applied: the 49.95% stake gave the Company decisive influence over the Polish Entity, qualifying the investment as an exercise of the freedom of establishment. This conclusion is unaffected by the Polish Entity's fiscal transparency, which is a purely tax characterisation that does not alter the commercial reality of the cross-border investment.
While acknowledging, with reference to several Court of Justice of the European Union ("CJEU") cases, e.g., Marks & Spencer (C-446/03), Bevola and Jens W. Trock (C-650/16) and W AG (C-538/20), that refusing to account for a transparent subsidiary's assets and liabilities could in principle constitute a disadvantageous treatment, the Higher Administrative Court rejected the challenge for lack of objective comparability. Applying Timac Agro Deutschland (C-388/14) and W AG (C-538/20), it held that, once Luxembourg had ceded taxing rights over the Polish property under the DTT, a company holding a domestic debt-financed asset is not in an objectively comparable situation to one holding a treaty-exempt foreign asset. No restriction on the freedom of establishment arose.
The so-called "definitive losses” exception developed under Bevola and Jens W. Trock (C-650/16) to address situations where a foreign permanent establishment generates losses that are permanently unrecoverable in the foreign state and cannot be taken into account at the level of the parent holding company in its state of residence was equally rejected: since Poland levies no NWT, no negative NWT basis could ever arise in that jurisdiction, and the Company already benefited from full NWT exemption under the Lux-Poland DTT - a further deduction in Luxembourg would amount to a double benefit. Deutsche Shell (C-293/06) was distinguished (the loss there was by nature only recognisable in the parent’s state), as was Heinrich Bauer Verlag (C-360/06) (which concerned a differential valuation method, not a full exclusion). Finally, the Higher Administrative Court declined to refer a preliminary question to the CJEU, invoking the acte clair doctrine - which holds that a national court of last resort is not required to refer a question of EU law to the CJEU where the correct interpretation is so obvious as to leave no room for reasonable doubt, as established in CILFIT (C-283/81) and confirmed in Consorzio Italian Management (C-561/19) - as articulated in the CJEU's judgment in Consorzio Italian Management (C-561/19). The appeal was dismissed in its entirety.
Practical implications
This judgment establishes a clear symmetry principle: where a foreign asset is exempt from Luxembourg NWT under a double tax treaty, the related financing debt is correspondingly non-deductible under Luxembourg domestic law. EU law, in particular the freedom of establishment, does not override this outcome; where the other contracting State levies no equivalent net wealth tax, no definitive unrecoverable loss can arise, and no double taxation is suffered.
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