Common Mistakes on Tax Returns and How to Avoid Them

Every year, many taxpayers in Switzerland make avoidable mistakes on their tax returns. These not only lead to unnecessary inquiries from the tax office but can also result in higher taxes or even fines.

This article explains the most common mistakes and how to avoid them with a few simple measures.

Mistakes Related to Deadlines

Submitting the Tax Return Late

A common mistake is submitting the return after the deadline (usually March 31). Late submission can lead to:

• Reminder notices from the tax office
• Penalties or fines
• In the worst case, a discretionary assessment

Tip: Request a deadline extension in time – in many cantons this can be done online for free.

Mistakes Related to Income and Assets

Incomplete Declaration of Income

Commonly omitted:

• Secondary income (e.g., freelance work)
• Pensions or daily allowances (disability, unemployment, sickness)
• Capital income (dividends, interest)

Incorrect Reporting of Assets

Often missing:

• Balances on foreign bank accounts
• Cryptocurrencies in the securities portfolio
• Vehicles or life insurance with surrender value

Tip: Collect all account statements, salary certificates, and asset records and declare them completely.

Mistakes Related to Deductions

Missing Important Deductions

Many taxpayers do not claim all available deductions, such as:

• Contributions to Pillar 3a
• Medical and accident costs not covered by insurance
• Donations to charitable organizations
• Professional expenses (commuting costs, office supplies, home office)

Claiming Incorrect Deductions

A common misconception is that rent or private living expenses are deductible.

Tip: Only claim legally allowable deductions and keep receipts carefully.

Mistakes Related to Real Estate

Not Declaring Imputed Rental Value

Many homeowners forget to declare the imputed rental value of their home.

Confusing Maintenance and Renovation Costs

• Deductible maintenance costs: Repairs, replacement of identical items
• Non-deductible value-increasing costs: Expansions, luxury renovations

Tip: Check invoices and classify costs correctly.

Mistakes Related to Documentation

Missing Documentation

Receipts for donations, medical costs, or renovations are often missing – without proof, deductions are denied.

Incomplete Records

Account statements as of December 31 or insurance certificates are often forgotten.

Tip: Collect all receipts digitally or in an annual folder.

Practical Examples

Example 1: Missing Pillar 3a Receipt

An employee in Zurich contributes CHF 7,056 to Pillar 3a but forgets to submit the receipt. As a result, he misses a tax saving of over CHF 2,000.

Example 2: Undeclared Side Income

A student works part-time as a freelancer and does not declare the income. The tax office requests a retroactive declaration and imposes an additional fine.

Example 3: Incorrect Renovation Deductions

A family renovates their kitchen and claims the full cost as maintenance. The tax office classifies part of it as value-increasing and adjusts the deductions.

Common Mistakes at a Glance

• Missed deadline → Penalties or discretionary assessment
• Incomplete income or assets → Additional taxes and fines
• Missing important deductions → Unnecessarily high tax burden
• Incorrect deductions → Adjustments by the tax office
• Missing receipts → Deductions denied

Conclusion

The tax return can be complex, but most mistakes are easily avoidable. Observing deadlines, fully declaring income and assets, claiming all deductions, and carefully collecting receipts saves time, stress, and most importantly, money.