DeadlinesUpdated:
The short answer
In most cantons, a deadline extension for the tax return can be applied for easily online or in writing, ideally before the original deadline expires. Depending on the canton, a first extension is free of charge, while further postponements are sometimes subject to a fee. It is important to submit the application in good time and with the correct details.
Why a deadline extension can make sense
Not all the necessary documents are always available by the original deadline, for example when salary certificates, bank documents or certificates from insurers arrive late. Personal circumstances such as illness or professional workload can also make an extension sensible.
A deadline extension applied for in good time is almost always simpler and cheaper than missing the deadline and going through the subsequent reminder procedure.
Anyone who has their tax return prepared by a specialist also often benefits from a deadline extension, as mandates are processed throughout the year and not all clients can be dealt with at the same time.
How to apply for a deadline extension
Most cantons offer an online form for the deadline extension, through which the application can be submitted with just a few details. Alternatively, a written or telephone request is often possible as well.
It is important to submit the application before the original deadline expires, as a retrospective extension after the deadline has passed is generally no longer granted.
In many cantons, the extension is granted automatically as soon as the application has been submitted via the official portal, without having to wait for an explicit confirmation. Nevertheless, it is advisable to keep a confirmation or proof of receipt so that, in case of doubt, you can demonstrate that the application was submitted on time.
- Go to the responsible online portal of the canton
- Enter your personal details and the tax period
- Indicate the desired new deadline or the length of the extension
- Submit the application before the original deadline expires
- Keep the confirmation from the tax administration
Cost and length of the extension
Whether a deadline extension is subject to a fee depends on the canton and in some cases on the number of extensions already granted. A first, short extension is often free of charge.
The new deadline is usually pushed back by several weeks to months, although here too the exact length is regulated differently depending on the canton.
Some cantons grade their fees according to the length of the requested extension or the time at which the application is made. An early application is therefore usually more advantageous not only from an organisational point of view but in some cases also financially compared with an application made later.
Multiple extensions and their limits
In many cantons, it is possible to extend the deadline several times, although the requirements may increase with each further application. A more detailed statement of reasons or a higher fee are not uncommon here.
At some point, however, the tax administration sets a final, definitive deadline after which no further extension is granted. This final deadline must be met at all costs in order to avoid a reminder or a discretionary assessment.
Anyone who can foresee that even the final deadline will be tight should seek a conversation with the tax administration early on instead of simply letting the deadline pass. Open communication is generally received better than complete silence.
Deadline extensions in special situations
In special life situations, for example prolonged illness, a death in the family or an exceptional professional workload, some cantons also grant a more generous deadline extension outside the usual procedure. A brief, factual statement of reasons is helpful here.
A longer deadline can also make sense in more complex tax situations, for example with foreign connections, properties in several cantons or self-employment, so that all the necessary receipts are fully available. In such cases, it is often also worth calling in a specialist to ensure that the details are submitted correctly and completely.
Anyone who regularly needs a longer processing time, for example due to recurring business financial statements or complex asset situations, can also ask the tax administration whether a longer deadline can be provided as standard for their situation. This creates planning certainty and reduces the administrative effort of repeated applications.
The deadline extension as a plannable step
A deadline extension is not an exception but a regular part of the procedure surrounding the tax return, which many taxpayers use on a regular basis. It is important to regard the application as a fixed part of your own planning and not to think of it only when the deadline is already very close.
Anyone who gets into a fixed rhythm for the annual tax return, for example with an early date for gathering the documents, can usually judge better whether an extension is needed at all or whether the original deadline can easily be met. In this way, the deadline extension can be used as a plannable tool rather than as a last resort shortly before the deadline expires, which generally leads to less stress and a more careful, more complete tax return.
What you should have ready
- Details of the tax period and tax number
- Login details for the cantonal online portal
- Desired new date for filing
- Statement of reasons, if one is required
- Overview of extensions already received
- Confirmation of the approved deadline extension
Frequently asked questions
Sources
General information, not individual tax advice. Status: August 2026. The current guidelines of your canton and the official information of the tax authorities are decisive.
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