Start with the tax year on your letter, not the year you open the filing software. Keep your deadline notice beside you as you work through this guide. It is general information, not a calculation of your personal tax liability.
Who must file a Swiss tax return?
Foreign employees without a settlement permit are generally taxed through payroll, subject to exceptions. This is Quellensteuer, or tax at source. It does not always replace a return. The Federal Tax Administration explains the system and links to cantonal authorities.
For Swiss-resident employees taxed at source, at least CHF 120,000 annual gross employment income triggers mandatory subsequent ordinary assessment. Other income or assets can also trigger it; check your canton rather than assuming that earning less means no return. In Zurich, part-year salary is annualised for this threshold. Source: Zurich withholding-tax rules.
If you received a return, do not discard it because payroll already deducted tax. Ask the issuing office to clarify anything you do not understand.
Which deadline applies in 2026?
There are two different tasks:
| Task | What to check |
|---|---|
| Submit an ordinary return | The deadline and any approved extension on your cantonal or municipal notice |
| Request voluntary subsequent ordinary assessment for 2025 | The separate March 31, 2026 request deadline, which has passed |
For example, Zurich directs taxpayers who cannot submit an ordinary return by March 31 to request an extension from their municipal tax office before the deadline. Its official filing page includes a municipality lookup. Do not apply Zurich's procedure to another canton without checking.
Already late? Contact the authority named on your notice promptly. Explain whether you missed the return itself or the assessment request. Do not assume that an extension or a refund is still available.
Does voluntary assessment guarantee a refund?
No. Tax already withheld is credited against the assessment, but the final balance can mean money back or an additional payment. For resident taxpayers, returns continue in subsequent years while source-tax liability continues. The federal guidance explains these consequences.
In Zurich, a properly submitted voluntary request cannot be withdrawn. A correction of an incorrect payroll tariff is a different procedure from requesting assessment to claim deductions. Check the canton's distinction before choosing a form.
Documents to prepare before opening the return
Use this as an organisation checklist, not a declaration that every item is deductible. Your canton may require other documents.
- Your filing letter: tax year, taxpayer reference, access instructions and deadline.
- Income folder: salary certificates and records for any other income relevant to your situation.
- Accounts folder: year-end statements for accounts and investments, including foreign holdings to discuss with the authority or adviser.
- Possible deductions folder: pension contribution certificates, insurance statements and receipts you want checked against the instructions.
- Changes folder: dates and documents for a move, marriage, separation or other relevant changes.
- Questions list: anything uncertain, with the relevant document attached. Resolve these before submitting rather than guessing.
Keep copies in a private folder. Never send tax records, identification documents or account statements through public community chats.
How to check deductions without mixing tax years
Open the instructions for 2025 when completing the 2025 return. A contribution paid in 2026 should not be treated as a 2025 expense merely because you are filing now.
Check each potential deduction separately: eligibility, evidence, applicable year and federal versus cantonal limits. Home-office spending, commuting and childcare are not automatically deductible in full. Avoid copying a nationwide allowance from an old blog post.
Zurich publishes year-specific instructions and an English introduction on its tax-return page. Other cantons have their own instructions. This guide intentionally does not offer a one-size-fits-all deduction total or promise tax savings.
Where to file
Use the portal linked by your cantonal authority or your filing letter. There is no single filing tool that this guide can prescribe for every canton.
For Zurich, start at the official online-return and support page. For withholding-tax questions elsewhere, use the federal directory of cantonal authorities.
Before submitting, check the year, personal details, attachments and unresolved questions. Afterwards, keep the submission confirmation with your documents. An assessment notice is a later document, not the same thing as confirmation that you submitted.
When to get individual help
Cross-border income, foreign property, self-employment, employee shares or a mid-year international move deserve individual review. Ask a qualified adviser for the scope and price of that review before commissioning it. Sweezy is not a tax adviser and cannot determine the correct filing treatment for your case.
Continue your Swiss admin checklist
- Swiss tax system for expats: the broader overview
- Moving to Zurich: registration and local contacts
- Find your canton guide
Keep the filing deadline, the authority's reply and your next action together. The aim is a complete, correctly routed return, not a rushed application for a refund.
