📋What you'll learn in this guide:
- March 31: The make-or-break deadline
- Quarterly Dates: When bills arrive
- End of Year: Pillar 3a & Insurance deadlines
- Penalties: Cost of missing dates
Missing a Swiss tax deadline costs you money. Real money. There's no "oops, I'll do it next year."
Here's your complete calendar.
The Big Date: March 31
March 31 is the most important tax deadline in Switzerland. Three different things happen:
The March 31 Triple Deadline
- Tax Return: Due for C permit holders & >120k earners.
- Tarifkorrektur: Deadline to correct source tax deductions (B permits).
- Nov adjustment: Last chance to switch tax status for the year.
If you miss March 31:
⚠️ Tax return: Extensions possible (apply in advance)
⚠️ Tarifkorrektur: No extensions. Money gone.
⚠️ Nachträgliche Veranlagung: No extensions. Opportunity lost.
2025 Tax Calendar
January
| Date | Action | Who |
|---|---|---|
| Jan 1-31 | Receive Lohnausweis from employer | Everyone |
| Jan 31 | 3a tax certificates arrive | 3a account holders |
Action: Gather all documents as they arrive. Don't wait until March.
February-March
| Date | Action | Who |
|---|---|---|
| Feb 1-Mar 31 | Prepare and file tax return | Ordinary taxation |
| Mar 31 | ⚠️ Tax return deadline | Ordinary taxation |
| Mar 31 | ⚠️ Tarifkorrektur deadline | Quellensteuer |
| Mar 31 | ⚠️ Nachträgliche Veranlagung request | Quellensteuer (optional) |
Action: Don't wait until March 30. Start in February.
April-September
| Date | Action | Who |
|---|---|---|
| Apr 1-Jun 30 | Extension period (if requested) | Extended filers |
| Jul-Sep | Provisional tax bill arrives | Home owners, assets |
| Sep 30 | Extended deadline (some cantons) | Extended filers |
Action: If you requested an extension, note your new deadline.
October-December
| Date | Action | Who |
|---|---|---|
| Nov 30 | Health insurance switch deadline | Everyone |
| Dec 31 | ⚠️ Pillar 3a contribution deadline | 3a savers |
| Dec 31 | Tax year closes | Everyone |
Action: Make your 3a contribution BEFORE December 31. Banks need processing time.
Deadline Details
Tax Return Extensions
You can request an extension in most cantons:
- How: Online portal or written request
- When: Before March 31
- Extension: Usually 1-6 months
Not all cantons offer the same extensions. Geneva allows up to June 30 online. Zurich can extend to July-August.
Tarifkorrektur (Source Tax Correction)
If you pay Quellensteuer and have deductions the employer didn't account for:
What you can correct:
- Pillar 3a contributions
- Large work-related expenses
- High medical costs
- Donations
How: Download the Tarifkorrektur form from your cantonal tax office, complete it, and submit by March 31.
Average refund: CHF 500-2,000
💡 Pro Tip: If you contributed CHF 7,056 to Pillar 3a, always file a Tarifkorrektur. The refund is almost guaranteed.
Nachträgliche Veranlagung
This is a request to be assessed under ordinary taxation instead of Quellensteuer. It makes sense if:
- You have significant deductions
- You own property
- You have complex financial situation
Binding for the year. Once requested, you can't go back for that tax year.
Deadline Penalties
| Deadline | Consequence of Missing |
|---|---|
| Tax return | Penalty fee (CHF 50-1000), estimated assessment |
| Tarifkorrektur | No refund. Money lost permanently. |
| 3a contribution | Contribution limit lost forever |
| Health insurance switch | Locked in for 12 more months |
The Tarifkorrektur is the harshest. There's genuinely no exception. Miss March 31 and that refund is gone.
Set These Reminders Now
Open your calendar and add:
- Feb 15: Start gathering tax documents
- Mar 15: Complete tax return OR submit Tarifkorrektur
- Nov 1: Review health insurance, decide on switch
- Dec 15: Make Pillar 3a contribution (don't wait until Dec 31)
Conclusion
Swiss tax deadlines are strict. The system doesn't bend for "I forgot" or "I was busy."
Mark March 31 in red. It's the deadline that costs expats the most money when missed.
And don't touch December 31 without your Pillar 3a contribution complete.
Read Next
- Swiss Taxes for Expats: Complete Guide – Understand the system
- Pillar 3a: The Smart Money Move – Why you should max it out
- Tax Calculator – Estimate your taxes
Frequently Asked Questions
What happens if I miss the tax return deadline?
You'll receive a reminder with a fee (CHF 50-200). If you still don't file, the tax office will estimate your taxes (usually higher than reality). You can still file late and correct it, but penalties accumulate.
Can I extend the Tarifkorrektur deadline?
No. March 31 is absolute. No extensions, no exceptions. If you're in Quellensteuer and want deductions corrected, submit the form before March 31.
When should I make my 3a contribution?
Ideally throughout the year (monthly contributions). At the latest: mid-December. Banks need 2-3 business days to process, so December 30 is risky.
Is the March 31 deadline the same for all cantons?
Yes. The federal deadline is March 31 for tax returns. Extensions vary by canton but the base deadline is consistent.
Set your reminders. March 31 comes faster than you think.
