Are you taxed at source in Switzerland? Discover how the Subsequent Ordinary Assessment (SOA) allows you to deduct real expenses and optimize your taxation.
9 minutes read | Updated on February 20, 2026
Author: Brice DELHOME
Every year, thousands of cross-border workers who are taxed at source leave a portion of their salary to the Swiss tax authorities. The reason? The tax deducted directly from the payslip is calculated according to a flat-rate scale that completely ignores your actual expenses (mortgage interest, childcare costs, pensions).
To restore equal treatment with Swiss residents, federal law allows cross-border workers to request "Quasi-Resident" status through a procedure called Subsequent Ordinary Assessment (SOA or TOU). However, this process follows strict calculation rules and contains certain pitfalls. Here is a detailed analysis to optimize your taxes without making a mistake.
👉 The concept: Replacing the flat withholding tax with a complete tax return allowing you to deduct actual expenses.
👉 The golden rule (The 90%): At least 90% of the worldwide income of your tax household must be generated in Switzerland.
👉 Main deductions: 3rd Pillar (3a), BVG/LPP buy-ins, childcare costs, mortgage interest for your home in France, continuous education costs.
👉 The strict deadline: The application must be filed with the Cantonal Tax Administration before March 31st of the following year.
👉 The risk: Since 2021, this choice is irrevocable. If your actual expenses are lower than the flat-rate ones, you will pay more tax. A preliminary simulation is mandatory.
As a cross-border worker (especially in the cantons of Geneva, Zurich, or Aargau), you are subject to Withholding Tax (ISO). Your employer deducts the tax directly from your gross salary according to a scale (e.g., Scale A for single, B for married).
This scale incorporates average flat-rate deductions. For example, it assumes you have normal commuting expenses or standard medical costs. However, it completely ignores your personal investments (pensions) or heavy expenses (mortgage).
The Subsequent Ordinary Assessment (SOA/TOU), granted via quasi-resident status, allows you to escape this flat rate. You will fill out a complete Swiss tax return (just like a Geneva or Zurich resident). The administration will calculate your exact tax. If it is lower than the tax deducted at source, you will be refunded the difference.
The tax administration is uncompromising on this condition. To qualify as a quasi-resident, at least 90% of the gross worldwide income of your tax household must be subject to taxation in Switzerland.
Concrete examples:
If you are eligible (the 90% is reached), you access the tax Holy Grail: the deduction of your real expenses. Here are the items that generate the biggest refunds:
| Deduction category | Details and limits |
|---|---|
| Tied pension (3rd Pillar A) | Full deduction of contributions up to the legal limit (approx. 7,056 CHF in 2026). This is the main driver for requesting the SOA. |
| Pension buy-ins (BVG / 2nd Pillar) | Amounts paid voluntarily to fill pension gaps are deductible (can represent tens of thousands of francs). |
| Passive interest (Loans & Mortgages) | You can deduct interest on your mortgage (even for a house located in France) or consumer loans. (Note: requires the declaration of worldwide wealth). |
| Childcare costs | Actual daycare or nanny costs (often capped at 25,000 CHF per child/year depending on cantons), justified by invoices. |
| Professional commuting costs | If the distance from home to work is significant. Note: since recent reforms, the deduction for private vehicles is strictly capped (e.g., max 3,000 CHF in Geneva). The SBB travelcard is preferred. |
| Alimony / Child support | Alimony paid following a divorce or for child support is fully deductible from taxable income. |
Applying for quasi-resident status is not a simple risk-free "attempt." This is where many cross-border workers make a costly mistake.
What happens if you request the SOA? The tax administration cancels your flat-rate withholding tax and recalculates everything from scratch.
Our expert advice: Never file an SOA request without first running an accurate simulation, either via your canton's official software (e.g., GeTax in Geneva) or by consulting a cross-border fiduciary or tax specialist.
The relevance of this status depends entirely on the canton where your employer is located, due to Franco-Swiss bilateral agreements.
This is the main playground for quasi-resident status. In the canton of Geneva, which did not sign the 1983 agreement, tax is systematically deducted in Switzerland. Requesting the SOA before March 31st is the normal procedure to claim a 3rd pillar or childcare costs.
In these cantons, the default rule is that the cross-border worker (who returns daily to France) is exempted from withholding tax in Switzerland (they pay their taxes to the French tax authorities). By definition, you cannot request an SOA to recover a tax that was never deducted.
Exceptions in these cantons: Quasi-resident status remains possible and relevant only for:
You have made your calculations, submitted your SOA, and the Cantonal Tax Administration (AFC) notifies you of excellent news: they will refund you 3,500 CHF in overpaid taxes!
Providing the Swiss administration with the IBAN of your French bank or European neobank. The tax office will send Swiss francs. Your bank will intercept this international transfer, deduct SWIFT processing fees (often 15 to 25 €), and most importantly, apply its own margin on the exchange rate. On 3,500 CHF, you can easily lose more than 80 € into the financial void.
🚀 The smart investor's solution (ibani):From automated salary repatriation to the conversion of your tax refunds, ibani is the Swiss army knife for your currencies.
Discover the ibani appThe request for Subsequent Ordinary Assessment (SOA) must be submitted absolutely before March 31st of the year following the receipt of income (e.g., before March 31, 2026 for income received in 2025). Past this date, the deadline expires and the flat-rate withholding tax becomes final.
No. Since the revision of the withholding tax law (effective in 2021), the SOA request is strict and irrevocable for the current tax year. If the final calculation established by the administration is against you, you will not be able to revert to traditional withholding taxation. A prior simulation is therefore indispensable.
Yes, this is one of the major advantages of the quasi-resident status (SOA). You can deduct the passive interest of your debts, including the mortgage of your main residence located in France. This deduction is made proportionally to the international distribution of your wealth (you will therefore have to declare the value of your property and the balance of your loan).
Do not miss any tax deadlines and discover our tips to maximize your purchasing power in Switzerland.
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