TF, 13.10.2026,2C_619/2026
Facts
On May 24, 2023, the Internal Revenue Service (IRS), acting as the competent authority for the United States of America, submitted a request for administrative assistance in tax matters to the Federal Tax Administration (FTA) based onArt. 26 of the U.S.-Swiss Double Taxation Convention (DTC CH-US) (Fact A).
The request sought to identify U.S. taxpayers (citizens, residents, or green card holders) who were direct or indirect holders of bank accounts with non-compliant tax status ("U.S. Penalty Accounts") at Banque B.________ AG between September 23, 2009, and December 31, 2019. This data had initially been provided to U.S. criminal authorities in redacted form as part of a 2020 plea agreement ("Plea Agreement" / "Report II.D.2"), and the IRS was now requesting the full, unredacted version (Fact A).
In a final decision dated April 4, 2025, the FTA granted the requested administrative assistance and consented to the transmission of bank data pertaining to the account held by A.________, provided that the transfer included a notice regarding usage limitations and the confidentiality of the information in accordance with Art. 26 para. 2 of the DTC CH-US (Facts B and B.a).
Following an appeal by A.________, the Federal Administrative Court partially upheld the appeal in a judgment dated September 8, 2026, formally ordering the FTA to clarify to the IRS that the transmitted data may only be used in proceedings brought against the individual in question for the facts specified in the request, while dismissing the remainder of the appeal (Fact B.b).
A.________ (hereinafter: the appellant) filed an appeal in public law matters with the Federal Supreme Court on October 1, 2026, primarily seeking the rejection or inadmissibility of the assistance request, and subsidiarily requesting a limitation on the data transmission or the referral of the case for a new decision (Fact C).
Law
Pursuant toArt. 83 let. h of the Federal Supreme Court Act (FSCA), an appeal in public law matters is inadmissible against decisions concerning international administrative assistance, except in tax matters, where the legal remedy is exceptionally available if the dispute raises a legal question of principle or if it is, for other reasons, a particularly important case within the meaning ofArt. 84 para. 2 FSCA (consid. 1.1).
The concept of a legal question of principle requires a novel legal issue that provides general guidance for resolving a multitude of similar cases pending before lower authorities, or that necessitates a reassessment of practice by the supreme judicial authority (consid. 1.1).
From the perspective of international treaties, the principle of good faith (Art. 26 of the Vienna Convention on the Law of Treaties) implies, in the field of the exchange of tax information, the principle of trust, under which the requested state must presume that the facts and statements presented by the requesting state are true (consid. 1.2.1).
The Swiss executing authority is therefore not required to verify the material accuracy of the facts presented, but merely examines the plausibility and the foreseeable relevance of the requested information in relation to the tax purpose pursued (consid. 1.2.1).
This presumption of accuracy binds the requested authority, even when the foreign authority has relied on information collected from an issuing bank, unless the person concerned rebuts this presumption with certain and indisputable evidence establishing a manifest inaccuracy from the outset (consid. 1.2.1 and 1.2.2).
Application to the specific case
The appellant first argues that the appeal raises the legal question of principle as to whether the principle of trust applies when the requesting state simply adopts the findings of a report prepared by a third-party bank ("Report II.D.2"), particularly when the individual alleges having validly renounced U.S. citizenship (consid. 1.2).
The Federal Supreme Court holds that this issue has already been resolved in the landmark judgment 2C_234/2025 concerning the same collective assistance request, with the high court explicitly confirming that the requested state is entitled to rely on the designation of the accounts under investigation even if the factual basis originates from the issuing bank's statements (consid. 1.2.2).
Furthermore, the loss or abandonment of U.S. citizenship does not automatically exclude the existence of other relevant tax ties to the United States that justify examining the account, meaning this question does not present a character of principle within the meaning of Art. 84a FSCA (consid. 1.2.2 and 1.2.3).
The appellant then raises the question of the scope of the duty to verify and exclude documents incumbent upon the FTA and the Federal Administrative Court when faced with data that he claims to have clearly refuted through documentary evidence (consid. 1.3).
The Supreme Court notes that this criticism actually only concerns the concrete application of the criteria of plausible relevance and the principle of good faith to the appellant's specific situation (consideration 1.3).
Such a challenge, limited to the assessment of the facts of the particular case, does not give the case any fundamental significance and does not justify a review on the merits (consideration 1.3).
As the restrictive admissibility conditions set out in Art. 84a of the Federal Supreme Court Act are not met, the public law appeal is inadmissible from the outset (consideration 1.4).
Outcome
The Federal Supreme Court declares the public law appeal inadmissible (operative part 1, recital 1.4).
The court costs, set at 5,000 CHF, are to be borne by the unsuccessful appellant (operative part 2, consideration 2).