Zurich tax deadlines and extensions: 31 March and what moves it (2025)

An extension can give you more time to complete an ordinary tax return. It does not extend the separate deadline for requesting an ordinary assessment when you pay tax at source. Check which deadline applies before making a request.

Key takeaways

• The 2025 return is due 31 March 2026. Extensions run to 30 September or, on request, 30 November.
• Extensions come from your municipal tax office (GemeindesteueramtGemeindesteueramtMunicipal tax officeITufficio fiscale comunale (GR only)Your municipality's tax office, which handles individual filings in Zurich. It is usually the right first contact, not the cantonal office.Where you see itThe sender of your filing notice and assessment.Open in the glossary →), not the cantonal one.
• A missed deadline cannot be extended, only reinstated. A reminder then gives you 10 days, and that one is not extendable either.
• An extension moves the filing date, not the payment date. Interest still runs around the 30 September general due date.
• The 31 March request for ordinary assessment or a TarifkorrekturTarifkorrekturSource-tax correctionFRrectification de l'impôt à la sourceITcorrezione dell'imposizione alla fonteA request to correct the figures your employer withheld on: a wrong tariff code, a wrong gross salary, or liability that never applied. It cannot be used to claim deductions; for those you need an NOV, by the same deadline.Where you see itRequested from the cantonal tax office by 31 March.Open in the glossary → cannot be extended at all: it is set by federal law.

Which deadline is yours

There is no national deadline. Each canton sets its own, and yours is the canton you were resident in on 31 December. Where you earned the money does not decide it. For Canton Zurich, the 2025 return is due 31 March 2026.

1. 1Documents arriveJanuary and February 2026
2. 2Return due31 March 2026
3. 3Extension, automatic for some groupsto 30 September 2026
4. 4Further extension, on request before the deadlineto 30 November 2026
5. 5Assessment arrivesmonths later, sometimes years

Who gets an extension, and how

Zurich's extensions (FristerstreckungFristerstreckungFiling extensionFRprolongation de délaiITproroga del termineA granted extension to the deadline for filing the ordinary return. It has to be requested, and it does not extend the source-tax deadlines.Where you see itRequested from your municipal tax office before the deadline runs out.Open in the glossary →) come from your municipal tax office (Gemeindesteueramt), not the cantonal administration.

• To 30 September, automatically, for two groups: the self-employed living in the canton, and people living outside Zurich who own property or run a business here. The directive calls the second group "L- und B-Fälle", where L stands for Liegenschaften (properties) and B for Betriebsstätten (business premises). That is not about L and B residence permits, and a B-permit holder living in Zurich gets nothing automatically.
• To 30 November, on request, which must arrive before your current deadline expires. 30 November is the ceiling the Weisung allows ("längstens bis 30. November"), not what a single request buys. The City of Zurich grants a first request to 30 September; a second request, filed before 30 September passes, is what reaches 30 November. Check the date on the confirmation rather than assuming which one you were given.
• Past 30 November, refused without extraordinary reasons. The directive names "my agent is busy" and "documents are missing" as not enough.

That L- und B-Fälle line is worth reading twice. It is the single most misread sentence in Zurich's filing rules, because the letters match residence-permit categories exactly. They are unrelated.

What a missed deadline actually costs

Ask for an extension before the current filing deadline. Once it has expired, an ordinary extension is no longer available. Reinstating the deadline requires a qualifying reason that prevented you from filing.

1. 1You miss the deadlineIt can no longer be extended, only reinstated
2. 2A reminder arrives (Mahnung)You get 10 days, and this one is not extendable
3. 3You still do not fileThe office estimates your income itself
4. 4The estimate landsEinschätzung nach pflichtgemässem Ermessen, rarely in your favour
5. 5A fine followsUp to CHF 1,000, or CHF 10,000 if repeated or serious

An estimated assessment is not a shortcut. You still owe the tax, and you have 30 days to object to a figure the office chose without your documents.

An extension moves the filing date, not the payment date

The two are separate clocks, and this catches people who assume an extension buys time on everything.

Cantonal and municipal tax in Zurich carries a general due date (VerfalltagVerfalltagGeneral due dateFRéchéance généraleThe date cantonal and municipal tax formally falls due, 30 September in Zurich, inside the tax year itself. Interest runs from it in both directions, whatever the date printed on your provisional bill.Where you see itNamed on the provisional invoice and on the final bill.Open in the glossary →) of 30 September of the tax year itself. That falls before the return is even filed, let alone assessed. Interest is calculated around that date, not around the date printed on your invoice. Pay before it and you earn credit interest (VergütungszinsVergütungszinsCredit interestFRintérêt rémunératoireWhat Zurich pays you on tax you handed over before the general due date. The mirror of Ausgleichszins, which is what it charges on anything still outstanding after that date.Where you see itSettled in the final bill, after your assessment.Open in the glossary →); leave it outstanding after and you are charged interest against you (AusgleichszinsAusgleichszinsCompensatory interestFRintérêt compensatoireInterest on tax still outstanding after the general due date. Zurich names the other direction separately: Vergütungszins is what it credits you on payments made before that date. A third rate, Verzugszins, applies once a final bill is overdue.Where you see itSettled in the final bill, after your assessment.Open in the glossary →).

Two cases with their own clock

• You leave Switzerland during the year. File for 1 January to your departure, that same year, within 30 days of the forms arriving. That is not the spring deadline, and by spring you may have no Swiss address or bank account left.
• A taxpayer dies. A separate return covers 1 January to the date of death, due within 60 days of the forms arriving.

The one deadline you cannot extend

Taxed at source and switching to an ordinary assessment (nachträgliche ordentliche Veranlagung), or requesting a source-tax correction (Tarifkorrektur)? That request is due 31 March and cannot be extended. It is set by federal law, so an extension on your ordinary return does not touch it, and leaving Switzerland ends the right the day you deregister (Abmeldung).

Nor is it a one-year experiment: once granted, ordinary assessment applies until your source-tax liability ends. See Quellensteuer: should you file?

Common questions

How do I request an extension?

Ask your municipal tax office (Gemeindesteueramt) before your current deadline lapses. A first, timely request is approved silently, but check which date it granted: the City of Zurich gives 30 September, and a further request before that date reaches the cantonal ceiling of 30 November.

I already missed 31 March. Can I still extend?

No. An expired deadline can only be reinstated, and only if something genuinely prevented you from filing. File as soon as you can. A reminder gives you 10 non-extendable days.

Sources

The sources below support the tax figures and rules discussed in this guide. Follow the links to check the original guidance and its scope.

1. Canton Zurich — Finance Directorate directive on the tax-return procedure: the 31 March deadline (G.I.1), the automatic extension to 30 September for self-employed residents and out-of-canton L- und B-Fälle (G.II.1), the on-request extension "längstens bis 30. November" and the rule that a timely first request counts as silently granted absent a written decision to the contrary (G.II.2), and the 10-day reminder period (G.IV.4). Issued 12 November 2025, in force 1 January 2026 — ZStB 132.1, zh.ch
2. City of Zurich — deadline extension for natural persons: an extension already granted to 30 September 2026 can be extended once more, on a further request filed before it expires, to 30 November 2026 at the latest — stadt-zuerich.ch
3. Canton Zurich — the public call to file, for the 30-day and 60-day periods when tax liability ends (30 days after the forms are delivered; 60 in case of death). The canton republishes this each year, so it now carries the 2026 period and 31 March 2027; the 31 March 2026 date for the 2025 return is source 5 below — ZStB 133.1, zh.ch
4. Canton Zurich — directive for returns when tax liability ends mid-year — ZStB 132.2, zh.ch
5. Canton Zurich — official guide to the 2025 return (form 305): the 31 March 2026 deadline, discretionary assessment, and the CHF 1,000 / CHF 10,000 fines, page 7 — zh.ch, PDF
6. DBGDBGThe federal income tax actFRLIFDBundesgesetz über die direkte Bundessteuer: the act that governs federal income tax for the whole country. Almost every federal rule a guide cites comes from here, which is why the abbreviation appears so often beside an article number.Where you see itIn citations, as DBG Art. 33 or similar. French and Italian sources call the same act LIFD.Open in the glossary → (SR 642.11) Art. 89a — the 31 March request deadline, the earlier cut-off at deregistration, and that ordinary assessment then runs until source-tax liability ends; Art. 119 para. 1 — deadlines set by the statute itself cannot be extended — fedlex.admin.ch
7. Canton Zurich — requesting a subsequent ordinary assessment or a source-tax correction: 31 March, non-extendable — zh.ch
8. Canton Zurich — Finance Directorate directive on collecting state and municipal taxes (ZStBZStBThe Zurich tax manualZürcher Steuerbuch: Canton Zurich's own practice manual, published in German only. It is where the canton writes down how it applies a rule in practice, which is often more specific than the law behind it.Where you see itIn citations as ZStB 132.1 or similar, wherever a Zurich-only practice is stated.Open in the glossary → 172.1): interest is computed so that payments made before 30 September are credited to the taxpayer and amounts still outstanding after that Verfalltag are charged against them, so payment on the day itself is in time — zh.ch