TF, 04.28.2026, 9C_641/2025
Facts
A married couple residing in Geneva, where the husband has professional training and experience in the art field, sold numerous pieces from their private art collection between 2010 and 2015. In their tax returns for these periods, they declared themselves unemployed with zero or near-zero income, while noting the sale of certain works to cover their living expenses. Following an investigation, the Cantonal Tax Administration (AFC) classified these sales as self-employed professional activity, noting the sale of at least 85 items for a total profit of over CHF 1.9 million over six years. The AFC issued a tax reassessment, calculating taxable income on this basis. (consid. A)
The taxpayers contested this assessment. The First Instance Administrative Court (TAPI) partially upheld their appeal and referred the case back to the AFC for a new assessment. Upon an appeal by the taxpayers, the Court of Justice of the Canton of Geneva upheld the TAPI judgment, validating the principle of taxing the sales as income from self-employed professional activity and the estimates made by the AFC. The taxpayers then appealed to the Federal Supreme Court, primarily challenging the method used to estimate the value of their collection and their cost of living, and, once again, the classification of their activity. (consid. B, C)
Law
The Federal Supreme Court reiterates that the scope of the dispute is defined by the claims and grievances raised before the lower court. A point of law not contested before the cantonal court becomes res judicata and cannot be re-examined by the Federal Supreme Court. Thus, if the classification of a self-employed professional activity was not contested at the cantonal level, it can no longer be challenged before the Federal Supreme Court. (consid. 3.2, 3.4)
The right to be heard (art. 29 para. 2 Cst.) guarantees the right of a party to express themselves, produce evidence, and participate in its administration. It includes an obligation for the authority to provide reasoning, but does not require it to order an expert opinion if it considers, without arbitrariness (anticipatory assessment of evidence), that it has sufficient elements to rule. Refusing to grant an extension to produce evidence is not a violation of the right to be heard if the party had ample time to produce it during the proceedings. (consid. 5.2, 5.4.2, 5.4.3)
In the absence of reliable accounting, the tax authority is entitled to proceed with an ex officio assessment by estimation (art. 130 para. 2 LIFD). It may rely on experimental coefficients, the evolution of assets, and the taxpayer's cost of living. It is then up to the taxpayer, who has failed to meet their procedural obligations, to prove that the estimate is "manifestly inaccurate." A simple objection or the production of partial evidence is not sufficient; proof that the estimate is erroneous must be complete. (consid. 6.1, 6.2)
The Federal Supreme Court examines the issue of the statute of limitations for tax assessment ex officio. For federal and cantonal income tax, this right expires five years after the end of the tax period, with the period being extended in the event of interruptive acts but not exceeding fifteen years in total (peremption period). The occurrence of the statute of limitations during proceedings must be noted ex officio. (consid. 4)
Application to the specific case
The Federal Supreme Court notes that the appellants did not contest the classification of their sales as self-employed professional activity before the cantonal Court of Justice; they limited themselves to criticizing the estimation method. Consequently, the question of the commercial nature of the sales is definitively settled and can no longer be examined. The subject of the dispute before the Federal Supreme Court is therefore limited to the method of estimating the value of the collection, the profit from the sales, and the cost of living. (consid. 3.3, 3.4, 3.5)
The Federal Supreme Court examines and rejects the grievances regarding the violation of the right to be heard. The Court of Justice sufficiently explained why it dismissed the private expert reports produced by the appellants (lack of methodology, appearance of biased expertise). The refusal to order a judicial expert opinion was not arbitrary, as the judges had sufficient elements, notably the taxpayers' own statements. The very short deadline granted to produce a new expert report was also not a violation, as the appellants had had years to prepare their evidence. (consid. 5.3, 5.4)
Regarding the assessment by estimation, the Federal Supreme Court judges that the AFC was entitled to proceed, as the appellants had not kept accounting records compliant with legal requirements for a self-employed person (art. 125 para. 2 let. b LIFD). The method used to calculate taxable profit—estimating the total value of the collection at CHF 1,200,000 based on the appellant's statements, dividing it by the number of items to obtain an average acquisition value, and then subtracting it from the sale price—is not deemed manifestly inaccurate. The appellants do not provide proof to the contrary, merely labeling it "absurd" without overturning it with probative elements. (consid. 7.1, 7.2, 7.3)
The estimate of the cost of living at CHF 400,000 per year (used to determine undeclared assets) is also validated. It is based on the appellant's own statements during hearings, where he admitted to monthly expenses of approximately CHF 25,000. The appellants fail to demonstrate the arbitrary nature of this finding. (consid. 8.1, 8.2)
Finally, the Federal Supreme Court notes ex officio that the right to tax for the 2010 tax period is time-barred, as the statute of limitations had expired by the time the judgment was rendered. The appeal must therefore be upheld on this specific point. (consid. 4, 10)
Outcome
The Federal Supreme Court partially upholds the appeal. It sets aside the judgment of the Court of Justice regarding the 2010 tax period, noting that the right to tax for federal and cantonal income tax for that year is time-barred, and cancels the corresponding taxes. For the remainder, namely the 2011 to 2015 tax periods, the appeal is dismissed to the extent that it is admissible. The court costs are partially charged to the appellants, who have only been partially successful. (consid. 1, 2, 3, 4 of the operative part)
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