Swiss Federal Supreme Court, 05.11.2025, 9C_353/2025
Facts
Following a criminal investigation for usury against A.A.________, the cantonal tax authority initiated tax back-payment and penalty proceedings against him and his spouse for the 2008 to 2015 tax periods, due to undeclared income and assets. The authority subsequently set a tax back-payment and a penalty.
Upon appeal, the Administrative Court of the Canton of Zurich partially upheld the challenge. It annulled the tax back-payment for the 2008 and 2009 periods due to the statute of limitations, but confirmed it for the 2010 to 2015 periods, setting the amounts at CHF 42,819.40 for direct federal tax and CHF 93,541.10 for cantonal and municipal taxes. The penalty proceedings were suspended. The taxpayers appealed this decision to the Federal Supreme Court.
Legal Principles
A tax back-payment is levied when facts or evidence unknown to the tax authority reveal that a tax assessment was omitted or that a final assessment is incomplete (Art. 151 para. 1 DBTA). This procedure aims to ensure correct taxation and does not depend on any fault on the part of the taxpayer.
Although the tax authority is subject to the duty of investigation, the taxpayer has a duty to cooperate (Art. 124 et seq. DBTA). If the taxpayer fails to fulfill their procedural obligations or if the tax elements cannot be reliably determined, the authority proceeds with an ex officio assessment based on estimation (Art. 130 para. 2 DBTA). Such an assessment can only be challenged by the taxpayer on the grounds of arbitrariness, i.e., if it is manifestly inaccurate (Art. 132 para. 3 DBTA). The taxpayer must then provide full proof of the inaccuracy of the estimate.
Application to the Case
The Federal Supreme Court finds it established that the appellant granted numerous loans to third parties over a long period, systematically and on a large scale, which amounts to a commercial activity. The appellants' argument that these loans were disinterested acts of solidarity is deemed implausible and dismissed as a mere defensive allegation.
The Federal Supreme Court notes that the appellants seriously breached their duty to cooperate by failing to provide the required documents and by providing contradictory information. This conduct placed the tax authority in a position of "evidentiary emergency" (Untersuchungsnotstand), legally justifying the use of an ex officio assessment based on estimation to determine the undeclared interest income.
The tax authority's estimation method, based on a documented case and applying a plausible average annual interest rate with a generous deduction for risk, is not considered arbitrary. The appellants failed to demonstrate that this estimate was manifestly incorrect. The Federal Supreme Court therefore confirms that it was justified to conclude, with near certainty, that interest had been received on all loans granted.
As the same principles apply to cantonal and municipal taxes, the decision is also confirmed on this point.
Outcome
The Federal Supreme Court dismisses the appeal to the extent that it is admissible. The tax back-payments for the 2010 to 2015 periods are confirmed. The legal costs are to be borne by the appellants.
Silex Tax Newsletter published in collaboration with Anna Vladau, Attorney at Law
