Swiss tax return deadlines 2026: due dates and extensions in nine cantons

The 2026 return is due in 2027

Swiss tax returns are always filed for the year that has just ended. The return for the tax year 2026 therefore lands on your desk at the start of 2027. In most cantons it is due on 31 March 2027. Zug and Thurgau allow until 30 April.

Not every canton has published its documents for the 2026 return yet. Basel-Stadt has released its 2026 guide, and Zurich and Geneva state a rule that applies every year. For the other cantons the table shows the rule that applied to the 2025 return; the exact 2026 dates are printed on the forms sent out in early 2027. All information is as at October 2026, tax year 2026.

If you only need the link to your canton's request form, FIN keeps a list of online extension portals for each canton.

Deadlines and extensions in nine cantons

Filing deadlines and extensions for the 2026 tax return, filed in 2027. Where a canton has not yet published its 2026 dates, the row shows the 2025 rule and says so. "No fee published" means the canton names no fee for a standard extension; that is not the same as a guarantee that it is free. Check your canton's portal before you rely on a date.

Three ways cantons handle extensions

Behind the details, the nine cantons follow three patterns:

• Extra time without asking. Basel-Landschaft adds two months to the printed date on its own. Aargau sends no reminders before 30 June. Zug approves requests up to the end of the year without even replying.
• Free at first, then a fee. Basel-Stadt is free until 30 September, then charges CHF 40. Basel-Landschaft charges CHF 40 once you need more than the automatic two months. In Zug, requests beyond 31 December need reasons and cost CHF 35.
• A fee or reasons from the start. Geneva charges from the first request, depending on how long you need. Thurgau expects a request with reasons to your municipality.

Zurich, Schwyz and St. Gallen do not fit neatly into any group, because they publish no fee for a standard extension. St. Gallen adds one condition worth knowing: an extension is only granted if your outstanding tax bills are paid.

Where you apply differs as well. In Zurich and Thurgau, the tax office of your municipality is in charge; the city of Zurich, for example, has its own online form for it. Basel-Stadt handles everything through the cantonal portal eSteuern.BS, Schwyz through efristen.sz.ch. In most cantons you do not need to give reasons. The exceptions are Geneva from November, Zug for requests beyond 31 December, and Thurgau, which always expects a reasoned request. Basel-Stadt also asks for good reasons and a reasonable advance payment if you need more time than the end of the filing year.

Example: the same delay in three cantons

Elena works in Geneva and holds a portfolio with a broker abroad. The foreign tax statement only arrives in late March, so she needs until the end of July 2027 for her 2026 return, about four months. She requests the extension in her online tax account in early March. Geneva charges CHF 40, because the extension is longer than three but shorter than five months.

Had Elena lived in Basel-Stadt, the same extension would have cost nothing, because it ends before 30 September. In Schwyz she would have had to request it before 31 March 2027 at efristen.sz.ch; the canton publishes no fee for that.

What an extension does not cover

An extension moves the date for handing in your tax return. It does not move every other deadline in the tax year. Four of them are often confused:

• Deadlines in a reminder. If the tax office has already sent a reminder, the date in it is strict. Zurich says outright that reminder deadlines cannot be extended.
• The request for an ordinary assessment if you are taxed at source. If you want to file voluntarily to claim deductions such as pillar 3a, the request must reach the tax office by 31 March of the following year. That date is fixed by federal law and cannot be extended.
• The request for the forms if filing is mandatory for you. If your assets or income not taxed at source cross your canton's threshold, you must ask for the tax return forms by the same 31 March. Our guide on when people taxed at source must file a tax return shows the thresholds by canton.
• The objection period. Once your assessment arrives, you have 30 days to object if something is wrong. That period cannot be extended either.

What happens if you do nothing

If neither a return nor an extension request arrives, the process runs through the same steps in every canton. First, the tax office sends a reminder with a new, short deadline. Some cantons charge for it: in Aargau the first reminder costs CHF 35 and the second CHF 50. If the reminder passes as well, the office assesses you at its discretion.

A discretionary assessment (Ermessensveranlagung) means the tax office estimates your income and assets itself, based on experience figures, how your assets have developed and your cost of living. The estimate is rarely low. Afterwards you can only challenge it by showing that it is clearly wrong, which takes more work than the original return would have. On top of that, failing to file despite a reminder can lead to a fine of up to CHF 1,000, and up to CHF 10,000 in serious or repeated cases.

The most frequent reasons for a late or incomplete return are covered in our article on the common mistakes in Swiss tax returns.

Checklist for the 2026 return

1. Note your canton's due date and whether extensions are automatic, free or charged.
2. Collect salary statements, pillar 3a and pension fund certificates, and the year end statement of every bank and broker, including accounts abroad.
3. If you already know you will be late, request the extension before the original deadline.
4. If you are taxed at source, check by mid March whether you have to file or want to: both requests are due on 31 March 2027.
5. In St. Gallen, pay any outstanding tax bills before you ask for more time.
6. When the assessment arrives, compare it with your return straight away; the 30 day objection period starts on delivery.

Every case is different, the deadlines are not

The dates in this article apply to the 2026 tax return. Cantons can change their rules from one year to the next, and some publish the final dates only with the forms. The details for your own return are on the form itself and on your canton's website, for example the Zurich tax return page, the Geneva page on extensions, the Basel-Stadt guide 2026, the Aargau page on filing, the Schwyz extension service and the St. Gallen extension page. This article gives an overview; it does not replace individual advice.

What does generalise: a late return is rarely the expensive part. The expensive part is a discretionary assessment, a missed 31 March deadline when you are taxed at source, or an objection period that runs out unnoticed. If you would rather hand over the paperwork, FIN prepares your Swiss tax return at a flat rate and keeps track of the deadlines for you.

Related FIN services

• Tax Return Switzerland
• Extension portals by canton
• B-Permit Tax Return
• Tax return obligation when taxed at source
• Swiss Tax Calculator