4 Common Swiss tax return mistakes (and how to avoid them)

Filing your Swiss tax return doesn’t have to be stressful, but even small mistakes can be expensive.

Every year, TrustFin sees individuals across Switzerland miss deadlines, overlook deductions or not realise they’re required to file a tax return at all. This can lead to unnecessary penalties, interest charges or paying more tax than needed, all of which could have been avoided with proper advice. 

Here are four common Swiss tax return mistakes and how you can avoid them:

1. Missing the Swiss tax return deadline 

While the Swiss tax return deadline is March 31 in most cantons,  many allow you to request a filing extension if you need more time.

If you miss the deadline without requesting an extension, it can lead to late-filing penalties, interest charges, and a discretionary tax assessment (often higher than necessary).

Find your canton’s tax deadline and extension request information here.

TrustFin Tip: Start earlier than you think you need to. TrustFin recommends gathering your documents as early as January, so you’re not rushing towards the due date.

2. Not realising you need to file a return (B permit holders) 

Many expats assume that paying tax at source in Switzerland means they don’t need to file a tax return. That’s not always the case.

You must file a Swiss tax return (in addition to paying at source) if:

• You hold a B permit and earn over CHF 120.000 per year, or
• Your monthly income exceeds CHF 10.000 (pro rata) 

Even if your income is below CHF 120,000, you may still need to file if you:

• Have significant assets
• Earn additional income (e.g. rental income, investments, side income)
• Live in a canton that requires supplementary filing 

TrustFin Tip: Don’t assume you’re exempt! Check your situation early using TrustFin’s B permit calculator. 

3. Not claiming Swiss tax deductions 

One of the costliest Swiss tax return mistakes is failing to claim all eligible deductions. Common Swiss tax deductions include:

• Work-related expenses 
• Health insurance premiums 
• Childcare costs 
• Pillar 3a contributions 
• Education and training costs 
• Property maintenance expenses 
• Wealth management fees 

Declaring the right deductions can save you thousands, sometimes even tens of thousands, of Swiss francs over time.

TrustFin Tip: Take some time to understand which deductions apply to your personal situation. Every canton has slightly different rules. You can find practical guidance on each type of tax deduction on TrustFin’s blog.

4. Doing it all yourself 

Navigating the Swiss tax system alone can feel overwhelming and complex, especially if you’ve recently moved to Switzerland, are filing in a second language or your financial situation has changed.

Many people try to complete their tax return alone anyway and hope for the best, but this often results in mistakes, missed deductions and unnecessary stress.

TrustFin Tip: You don’t have to do it alone. TrustFin’s tax experts are here to help you:

• Ensure compliance with canton-specific rules
• Identify all eligible deductions
• Reduce the risk of penalties
• Optimise your tax position 

Ready to skip the stress?

Book in a 30-minute introductory call now!