Swiss Federal Supreme Court, 19.01.2026, 9C_711/2025
Facts
For the 2021 tax year, a couple declared a taxable income of approximately CHF 57,500 (federal direct tax) and CHF 49,100 (cantonal/communal tax), with zero net wealth. Following an audit, the Federal Tax Administration (FTA) discovered that the husband had purchased over 100 vehicles for a total value exceeding CHF 200,000 and notified the Zurich cantonal tax authorities.
When asked to provide documents and information regarding these transactions, the couple failed to provide a substantive response, even after receiving a formal notice. The tax authority subsequently issued a default assessment, adding CHF 90,000 in self-employment income (vehicle trading) to their taxable income.
The taxpayers challenged this decision, claiming their profit was only CHF 3,000. Their subsequent objections and cantonal appeals were rejected. They then appealed to the Federal Supreme Court.
Legal Analysis
The Federal Supreme Court reiterates the requirements for the grounds of an appeal (Art. 42 para. 1 and 2 of the Federal Supreme Court Act). The appellant must concisely explain how the contested act violates the law, referring to the reasoning of the previous decision. Criticism that is purely appellate in nature, merely asserting one's own version of the facts without demonstrating a violation of the law, is inadmissible.
In tax matters, taxpayers have a duty to cooperate to ensure a complete and accurate assessment (Art. 126 para. 1 of the Federal Direct Tax Act). If they fail to fulfill this obligation despite a formal notice, or if tax elements cannot be reliably established, the tax authority shall proceed with a default assessment based on its own discretion (Art. 130 para. 2 of the Federal Direct Tax Act). Such an assessment can only be challenged if it is deemed fundamentally inadmissible or if the result is manifestly incorrect (Art. 132 para. 3 of the Federal Direct Tax Act).
Application to the present case
The lower court ruled that the default assessment was justified because the taxpayers had failed to meet their duty to cooperate by not providing the required information regarding their vehicle trading activities. It also found that the taxpayers failed to prove that the estimate of CHF 90,000 in additional income was manifestly incorrect, describing their explanations as contradictory, incomplete, and lacking credibility.
Before the Federal Supreme Court, the appellants do not challenge the reasoning of the cantonal judgment in any way. They limit themselves to general, unsubstantiated assertions (claiming to have sold only six vehicles) and argumentative criticisms (questioning the possibility of purchasing more than 100 vehicles for 200,000 CHF).
The Federal Supreme Court notes that the appeal contains no legal argumentation demonstrating how the contested decision violates federal law. The reasoning is therefore manifestly insufficient within the meaning of Art. 42 LTF.
Outcome
The Federal Supreme Court declares the appeal inadmissible due to its manifestly insufficient reasoning (Art. 108 para. 1 let. b LTF). The court costs, amounting to 1,000 CHF, are to be borne by the appellants, jointly and severally.
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