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Back-Tax Proceedings (2026)
Note: This language version is an automatically generated translation. The text may therefore contain linguistic and terminological errors.
view in original language (German)Note: This language version is an automatically generated translation. The text may therefore contain linguistic and terminological errors.
view in original language (German)Retroactive taxation of tax periods for which assessments have already become final requires the existence of a “new fact”—and in practice, it is precisely this question that determines whether the tax authority is permitted to make retroactive corrections or must accept that its own omissions can be held against it. The six case studies by lic. iur. Peter Hösli use concrete scenarios—ranging from violations of the blocking period in the 2nd pillar to pro memoria declarations and simplified reassessments for heirs—to illustrate how case law and practice address these issues. Benefit from clearly reasoned solutions that you can apply directly to your own cases.
In January 2019, Mr. Berner filed his 2017 tax return with the tax office. In it, he claimed a deduction of CHF 100,000 for a contribution to his pension fund. As early as June 2018, the same pension fund had made a lump-sum payment of CHF 150,000, which was taxed separately in October 2018. In December 2019, he filed his 2018 tax return. The lump-sum payment was reported on that return.
In June 2020, the tax office reviewed the 2017 tax return and, in doing so, overlooked the lump-sum withdrawal that violated the waiting period (Art. 79b(3) BVG) and initially allowed the deduction. The tax office did not notice the error until much later, during the review of the 2018 tax return.
In 2010, Mr. Karlen inherited a painting by a famous artist. Experts estimated the painting’s value at between CHF 1.5 and 2 million. The imputed value for the division of the estate was CHF 2 million; it was subsequently insured for CHF 2.5 million. Mr. Karlen declared the painting on his tax returns for 2010–2023 under “other assets” with the notation “Painting/Art” and an asset value of CHF 1. In 2026, he sold the painting for approximately CHF 7 million. The tax returns for 2010–2023 had already been definitively assessed by that time.
The Swiss AG has its headquarters in the canton of Zurich and operates various branches in other cantons, including one in the canton of Geneva. The Geneva tax administration assesses the branch there for a tax period even before the canton of headquarters takes action. One year later, the Zurich Cantonal Tax Office informs the Geneva tax authorities that it has made significant corrections. These corrections directly affect the tax allocation and, consequently, the taxation of the branch in the Canton of Geneva.
Can the Geneva tax administration make the corrections in a back-tax assessment proceeding?
Mr. Giovanni owns 500 shares of S. AG. According to the commercial register, S. AG has a share capital of CHF 500,000 (500 shares at CHF 1,000 each). From 2018 to 2021, he reported only 100 shares; however, in the 2019–2021 tax returns, the securities list still included a note stating that this represented a 100% ownership interest. The Graubünden Tax Administration calculated and assessed the value of the 100 shares in each instance using a flat-rate deduction of 30% for minority interests. In the 2022 tax return, Mr. Giovanni declared 500 shares; however, the Graubünden Tax Administration once again calculated the wealth tax value based solely on 100 shares (including the minority deduction), because it assumed the taxpayer had made an error, since no additional purchase of shares had been declared. Based on the clarifications made the following year (regarding the 2023 tax return), the tax administration recognized that Mr. Giovanni had actually owned 500 shares from 2018 to 2022 and that only 100 shares had actually been taxed.
Can all tax periods (2018–2022) be corrected through a back-tax procedure?
Mr. Conradin claimed a deduction for spousal support in the amount of CHF 10,000 for the years 2016–2022. In the 2016 tax period, the tax office investigated the spousal support. Mr. Conradin submitted portions of the divorce decree and a confirmation from his ex-wife stating that he had paid CHF 10,000. The divorce decree would have shown that this was a lump-sum payment of spousal support for the next 6 years, which was settled as a one-time payment (CHF 60,000) in 2016 as part of the division of marital property. The deduction in the amount of the declared CHF 10,000 was erroneously granted for 2016, and the divorce decree was filed in the permanent records. In each of the years 2017–2021, Mr. Conradin submitted a receipt signed by his ex-wife stating that he had paid alimony in the amount of CHF 10,000 in the respective year, which was accepted by the tax office. In the 2022 tax period, the alimony payments were reviewed again and, following further investigation, disallowed.
Mr. Müller passed away in June 2026. The heirs (two children and his wife/widow) discovered gold bars in a safe. The gold had not been declared previously. The wife was unaware of this. In addition, there is a joint account with the widow that has also not been declared to date. The 2024 tax year and all prior years have been legally assessed.
