Federal Supreme Court, 20.03.2026, 9C_167/2026
Facts
Taxpayers A.A.________ and B.A.________ challenged their 2019 tax assessment, which included the addition of a taxable benefit in kind of CHF 840,000. They filed an appeal against the decision on the objection with the Tax Law Chamber of the Court of Appeal of the Canton of Ticino.
Informed by the tax administration that the appellants had tax arrears, the Tax Law Chamber ordered them on December 29, 2025, to pay an advance on costs of CHF 5,000 by January 20, 2026, to guarantee the payment of legal costs. The order explicitly stated that in the event of non-payment within the prescribed period, their appeal would be declared inadmissible, in accordance withArt. 231 para. 1 of the Ticino Tax Act (LT/TI).
As the taxpayers did not make the payment within the set deadline, the President of the Tax Law Chamber declared their appeal inadmissible on February 4, 2026. The taxpayers then appealed to the Federal Supreme Court, requesting the annulment of this inadmissibility decision and the referral of the case back to the cantonal authority for a review on the merits.
Legal Grounds
The dispute submitted to the Federal Supreme Court does not concern the merits of the taxation (the CHF 840,000 benefit), but exclusively the decision of inadmissibility issued by the cantonal authority due to the failure to pay the advance on costs.
Article 231 para. 1 LT/TI authorizes the cantonal judicial authority to require appellants who do not reside in the canton or who are in arrears with their tax payments to provide a guarantee for procedural costs. Failure to pay this guarantee within the prescribed period results in the inadmissibility of the appeal.
Before the Federal Supreme Court, the scope of review is limited. In accordance withArt. 105 para. 1 of the Federal Supreme Court Act (LTF), the Court is bound by the facts established by the previous authority, unless they are manifestly inaccurate or established in violation of the law. New facts and evidence are in principle inadmissible (Art. 99 para. 1 LTF).
Furthermore, when appellants invoke the violation of constitutional rights (such as the prohibition of arbitrariness, equal treatment, or excessive formalism), they are subject to a strict requirement of substantiation (Art. 106 para. 2 LTF). They must explain clearly and in detail the nature of the alleged violation.
Excessive formalism, prohibited byArt. 29 para. 1 of the Constitution, occurs when the strict application of a procedural rule is not justified by any interest worthy of protection, becomes an end in itself, and makes the realization of substantive law or access to justice insupportably difficult.
Application to the specific case
The Federal Supreme Court examined and rejected all the grievances raised by the appellants.
- Grievances of arbitrariness (Art. 9 Const.) and discriminatory treatment (Art. 8 Const.): The appellants argued that the requirement for an advance on costs was arbitrary because they already had an CHF 80,000 deposit with the tax authorities. They also alleged discrimination, as the two companies behind the disputed service, which had also appealed and had tax arrears, were not required to pay such an advance. The Federal Supreme Court dismissed these arguments on the grounds that they were based on facts (the existence of the CHF 80,000 deposit, the companies' appeals, their tax situation) that had not been established in the challenged cantonal decision. Pursuant to Art. 105 para. 1 LTF, the Federal Supreme Court could not take these new elements into consideration. It further noted that the appellants should have raised these issues before the cantonal authority before the payment deadline expired.
- Grievance of excessive formalism (Art. 29 para. 1 Const.): The appellants believed that the application of Art. 231 LT/TI was too "rigid." The Federal Supreme Court found this grievance unfounded. It reiterated that case law does not identify excessive formalism when the requirement for an advance on costs and the consequences of non-payment are based on a clear legal basis, and when the parties have been duly informed of the amount, the deadline, and the potential penalty. This was the case here.
- Grievance of violation of the right of access to a court (Art. 29a Const.): The appellants complained that their appeal was declared inadmissible before those of the legal entities concerned were even processed. The Federal Supreme Court also rejected this grievance, as it too was based on facts not established in the cantonal proceedings.
The Federal Supreme Court concluded that the appellants' criticisms were either insufficiently substantiated within the meaning of Art. 106 para. 2 LTF or based on inadmissible new facts.
Outcome
The Federal Supreme Court dismissed the appeal. The decision of inadmissibility issued by the Tax Law Chamber of the Court of Appeal of the Canton of Ticino is therefore confirmed. The court costs for the federal proceedings, amounting to CHF 3,000, were charged jointly and severally to the appellants. The request for suspensive effect became moot.
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