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Tax authority letter in Switzerland: what should you do in the first 24 hours?

Received a Swiss tax authority letter? The 30-day appeal deadline is strict and missing it results in loss of rights. Learn the rules on appeals, instalment payments, and 2026 default interest.

Publisher: svajc.com Knowledge Base9 min readLast reviewed: 7/13/2026
Editorially reviewed
Table of contents
  1. Which letter have you received: a tax assessment decision or a tax bill?
  2. How and by when can you appeal to the Swiss tax authority?
  3. What should you do if the tax cannot be paid in one lump sum?
  4. What is the default interest rate in 2026, and from when does it start accruing?
  5. Cantonal differences: special rules in Zürich and Bern
  6. Hungarian-specific points: what should Hungarian taxpayers living in Switzerland watch out for?
  7. Sources

Which letter have you received: a tax assessment decision or a tax bill?

The very first, critical step is to identify the type of letter, because this determines what legal remedies are available.

There are two documents that are easy to confuse:

  • Tax assessment decision (Veranlagungsverfügung / Décision de taxation): this is the authority’s official decision on the amount of your taxable income and assets, and therefore how much tax you owe. This is the document that can be meaningfully challenged through a legal remedy.

  • Tax bill or final bill (Steuerrechnung / Schlussabrechnung / Bordereau d'impôt): this requests payment of the assessed tax. As a rule, you generally cannot dispute the amount of the tax through the bill itself, only at most technical billing errors.

The distinction is highly important in practice. Anyone who tries to appeal the final bill because they consider their tax too high is knocking on the wrong door: the amount of tax is set by the tax assessment decision, and it can only be challenged by appealing that decision.

This is why your first step should be to read the heading and title of the letter carefully. The type of document (Verfügung, Rechnung, Schlussabrechnung) and the information on legal remedies (Rechtsmittelbelehrung) are almost always shown at the top of the document.

Also record the date of receipt. For registered mail, the relevant date is the day you accepted delivery from the post, and that is when the 30-day clock starts.

How and by when can you appeal to the Swiss tax authority?

You must file an appeal (Einsprache / Réclamation) against the tax assessment decision within 30 days of receipt. This is a preclusive deadline.

A few basic rules worth keeping in mind:

  • The 30-day deadline will not be extended by the tax authority. If you miss it, the decision becomes final and legally binding, and the tax set out in it becomes definitive.

  • The deadline runs from the receipt of the decision, not from its date and not from the date it was posted.

  • The appeal must be in writing must be submitted to the competent cantonal tax office.

  • The procedure is generally free of charge — no fee is charged simply for filing the appeal.

The appeal must clearly identify which decision is being challenged (date, reference number) and what the taxpayer objects to. In many cantons, even a simple, unsubstantiated objection may be admissible, but it is in the filer’s own interest to state item by item which entry is being contested and why, and to attach supporting documents (e.g. proof of deductions).

An important timing point: if the 30th day is approaching but the evidence is still being gathered, filing within the deadline remains the priority. It is usually possible to provide missing documents later, but restoring a missed deadline afterwards is extremely difficult.

An appeal does not automatically suspend the payment obligation, and — as explained below — default interest continues to accrue during the appeal process.

What should you do if the tax cannot be paid in one lump sum?

If the tax cannot be paid in a single amount, payment relief (Zahlungserleichterung / Facilités de paiement) can be requested. It is advisable to initiate this before the payment deadline expires.

There are two main types:

  1. Installment payments (Ratenzahlung / Paiement par acomptes): the tax debt is paid in several smaller installments according to a schedule.

  2. Payment deferral (Stundung / Sursis): postponement of all or part of the payment to a later date.

The payment deadline is generally 30 days, and it is advisable to apply for relief before it expires. Anyone who waits until the first payment reminder (Mahnung / Sommation) arrives starts from a weaker position and may be pushed toward debt enforcement proceedings.

The application typically needs to explain why payment cannot be made in a single amount and what schedule is realistic. The authority assesses the situation; good-faith, proactive communication matters a great deal here.

One point, however, is important to understand clearly: payment relief does not eliminate default interest. Even while an installment plan is in place, interest continues to accrue on the outstanding balance.

What is the default interest rate in 2026, and from when does it start accruing?

The default interest rate (Verzugszins / Intérêt moratoire) on direct federal tax (Direkte Bundessteuer, dBSt / Impôt fédéral direct) from January 1, 2026, is 4.0%. This is a decrease from 4.5% in 2025.

The reduction was decided by the federal finance department in September 2025. The interest rate is therefore not fixed: it may change from year to year, so the value announced for the given year must always be taken into account.

The most important, and often misunderstood, point: default interest continues to accrue even if the taxpayer has filed an appeal, and also if payment by instalments has been approved. Neither ongoing appeal proceedings nor an approved payment arrangement stops the interest clock.

This has a practical consequence. If someone appeals because they consider the assessed tax too high, but the appeal is ultimately unsuccessful, interest continues to accrue on the full debt even during the appeal period. For this reason, many taxpayers — even where the amount is disputed — consider paying the disputed tax in advance and then reclaiming it if they win, precisely in order to reduce the interest risk.

Default interest on cantonal and communal taxes may differ from this, so the federal 4.0% should not automatically be applied to every type of tax.

Cantonal differences: special rules in Zürich and Bern

In Switzerland, a significant part of tax matters falls within cantonal jurisdiction, so the rules on payment by instalments and interest vary from canton to canton. The following two examples clearly show how different the practice can be.

Canton of Zürich — online payment by instalments:

  • Payment by instalments can be requested online.

  • According to an earlier draft, the maximum term up to 5 years, and the instalments were at least CHF 1,000 per tax type.

  • The exact conditions may vary by tax type, so in a specific case it is worth checking the current parameters on the canton’s official website.

Canton of Bern — advance-payment (akonto) bills and final bill:

  • The amount of the instalment (akonto) bills can be adjusted independently via e-banking, while keeping the reference number unchanged. This provides flexibility for advance payments during the year.

  • However, for the final invoice (Schlussabrechnung), this is not enough: a separate request must be submitted for payment relief.

  • In canton Bern, the late-payment interest on cantonal taxes is 4.0% in 2026, which is the same as the 2024–2025 level.

The lesson can be generalized: what works in one canton (e.g. changing the amount independently in e-banking) may require a formal request in another. Checking the official tax website of your own canton is essential in every case.

Hungarian-specific points: what should Hungarian taxpayers living in Switzerland watch out for?

A few considerations specifically relevant to readers with a Hungarian background:

  • Language barrier. Tax authority letters arrive in the canton’s official language (German, French, or Italian). The 30-day deadline does not stop simply because translating the letter took time. After receipt, it is advisable to clarify immediately what type of letter it is and what the notice on legal remedies (Rechtsmittelbelehrung) says, including by seeking help if necessary.

  • Withholding tax (Quellensteuer) situation. Many Hungarian employees have their wages taxed directly at source by their employer. In such cases, the nature of the letters and the route of appeal may differ from those of an ordinary tax assessment; here too, identifying the type of letter is the first step.

  • Double taxation. A double taxation agreement is in force between Hungary and Switzerland. If the letter concerns income that may also be taxable in Hungary (e.g. property in Hungary, pension income), the situation is more complex and involving an expert may be justified.

  • Moving away, returning home. If someone has left the canton or Switzerland, the authorities will send mail to the last known address. Keeping your address up to date is crucial; otherwise, the 30-day deadline may expire without the person concerned even learning about the letter.

Sources

- https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQFMU8-o6mLgR5VpGRLlxTmzWZYrsPudboOEnQYE6UJs-LSA4fSfK-TJAgXFp9FK6xwTrK8EjttFBlXVcIv0T4DLaObITTwA_Yh2EEwbk-IIn0lWNbaGK22_1GZp-x7Okb6L6JAjC7l3ygVM4b1pNmdnnBRvk10= - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQEPv0XTQXzbi5HKekIjpsiQYBUdz1GawlVPK5b3btDuhSnnramatiEB_bbF-LgIrSPHCq9RLRbkOS5OtbIZ_vUbIyIrEj3uKoScjRnyu9lwivREiZNNrgwpyLQNwzvuxH7U0pKsKdSn7UTFq9u6fkM9L2J5e58_xHBVbd-xju7rng7So8cl2Ldl4D_TsFepxn8pGbCPG3MJqzYCQg== - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQGA8U0QOYGK5FCAijnLV2TahHjZT65kELBQWa-vHEorozrQbEzdAcK2k6BchBtGDcX8D4VuY2TQVgjpI3c11S0FSuZsTriv2TIEqyOLT9nrwvRyFOMgiqOH4WUn9jyDjzJ-rnNDNHvo8RoSPUioynd-Muc5jcwvCyerOqM= - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQFZgGwmqx6JV1KhtPgTVywtKHukO3pmiTY55eZVNt2bHZcbYEP7_FfpIsLY43o2PYrZvyDYlN27HYhKKnhjcxoXB03CwdOiE-ssv6B6yGCWOa6wTtBpi-IR10DrSC1taT6pInidrn7OS-DyuiOxuZkkb7k8j0s= - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQGctqFKMPtRWTa7ZVZmJD9v0rZ92UGrk6iDRiZ-EdF0b_yt7US-Hx7S6znFXdwQZq60JxdvvyWox-UytNz-UHZpimxlTb1BUcNtEdQkniJy-Z38_ze9yLHweHVHBUgU2ziX6-wM7GdGh2KvHhFcpwWwQgxFFkR35plwUTYR1tBRwkRbPCQbCpznfE2BAYAcPn7TvsiemXeHqo_DlWoGYKpHZNGh8i4boWdrdySOVHaHXhfRp9ZVFWNEJwNM8-eEn9ALa8sWzVayybTp - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQFb31vxKsG6APEOQqc2o3sCfBNux0aNljB7uzhOO5g3xXwA9YKX93Ixw_VMLv2M1u-oGDzFkKMH28xIVSqnhRXuJ15emfcraS7A9vleVGhFMl7JUFvXR3clqMtid5EJpm2vZqmlt3Xk_bS39Z-Dx9gmHmXOUMRTuMoIaaQ0uH-vW9LHKfz6_5BDy65Rsw== - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQGdPR-QiksXpOhyCIVXF-i4UdYuA83IyBAS2EZVR4n49P_6DIhVvw1QJ_7PZJRJyMoZrNJUITEPnSfaO2nSUn_kIJG6ZLW_FUbmF4COeBuolaSZ21C15Q_UflbiAFsIzmp-EaiMv5qRA4JhCKomJp07hjaLvkdT9ItJ8ugtQ_AU8CfkEzIZOHhHus4c_X7vaKsf - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQG26Cl8-DqiLGRaVfSc_79DcHcQd9WnxnYIIioXg0HJG8aucyFRsF3DZJ2GkbAovkPXSy1d4LMdjB9IMHrYeFetfSpTQ9Sk1Zrr5iUbhJutVtPhl_tJ0u7z27MqqCAUYcJmG59nJn-OIDg= - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQGGhL4UqfKm4-3M4HsAHj-Fji7I_8_qqTeKME9CQS9415rmTJnbDWrwzZzdOnmF1M305p87N5bDBDnPHPU70iwpDqxsDdgxPssJNI5cAc_QfuZXbn8HtI9wUFU1EaDnC-IUNM2sV5gWwUo9O1m78iNC62AMZqBGDAkLr-g= - https://vertexaisearch.cloud.google.com/grounding-api-redirect/AUZIYQFiG6lGtmT_B4-aFLWmhEQIbP7h60MUJADqeQrFlCddH4wlFDK31HDN6W-6TUHvRPF1ssun4aZu1Izfg3cJI-3J5Jn6aHarsBY17oiarvdEMi6H-SQi8-lcXTdOQBzVvI5YpJx6C32k_VLrTFfSUB58LWLpuxpS_COxnOEHFtOWDgXNoDkXgdz7F1EUOZMnkSxi7hrNqtp-KbtL7fCX3Y__

In Brief

If you receive a Swiss tax authority letter, your first step is to determine whether it is a tax assessment decision (Veranlagungsverfügung) or merely a tax bill — because only the former can be meaningfully challenged, and it is subject to a strict 30-day appeal deadline that cannot be missed without losing rights. Default interest (4.0% for direct federal tax in 2026) does not stop running during either an appeal or an approved instalment arrangement, so prepaying the disputed amount may also be a strategy worth considering.

Key Takeaways

  • As soon as you receive the letter, check the heading: a Veranlagungsverfügung (tax assessment decision) can be appealed, while a Steuerrechnung (tax bill) generally cannot.
  • Record the exact date of receipt — the strict 30-day appeal period starts on the day you receive the registered letter, not on the date shown on the letter.
  • If you are still gathering evidence, submitting within the deadline takes priority; it is typically possible to supplement the file later, whereas reinstating a missed deadline is extremely difficult.
  • If you are facing payment difficulties, it is advisable to apply for an instalment arrangement or payment extension before the payment deadline expires — once debt collection has started, your position deteriorates significantly.
  • Bear in mind that default interest (4.0% for direct federal tax in 2026) continues to accrue during both an appeal and an approved instalment arrangement; consider prepaying the disputed amount and reclaiming it if you ultimately prevail.
  • If you are a taxpayer with a Hungarian background, pay particular attention to the language barrier: the 30-day deadline does not pause while a translation is being prepared, so the type of letter and the Rechtsmittelbelehrung (information on legal remedies) must be clarified immediately, with assistance if necessary.

Frequently Asked Questions

What is the difference between a tax assessment decision and a tax bill in Switzerland?

A tax assessment decision (Veranlagungsverfügung) is the authority’s formal decision on taxable income and assets, and this is the document that can be challenged by appeal. A tax bill (Steuerrechnung / Schlussabrechnung) merely requests payment of the assessed tax; at that stage, the amount of tax can no longer be disputed, only technical billing errors. In almost all cases, the heading of the letter and the Rechtsmittelbelehrung (information on legal remedies) indicate which type of document it is.

How much time do you have to appeal a Swiss tax assessment?

You have 30 days from receipt of the tax assessment decision to file an appeal (Einsprache / Réclamation) with the competent cantonal tax authority. This deadline is strict: if you miss it, the decision becomes final and the tax becomes definitive. The time limit runs from the date of receipt, not from the date shown on the letter.

Does filing an appeal stop default interest from accruing?

No. Default interest continues to accrue on the outstanding amount regardless of whether an appeal has been filed. If the appeal is ultimately unsuccessful, you will also have to pay the interest that accumulated during the entire appeal period. For this reason, many taxpayers consider paying the disputed amount in advance and reclaiming it if they ultimately win.

How high is default interest in Switzerland in 2026?

From 1 January 2026, default interest on direct federal tax (Direkte Bundessteuer) is 4.0%, which is lower than the 4.5% rate in 2025. Default interest on cantonal and communal taxes may differ — for example, in the canton of Bern it is also 4.0% in 2026, but you should always verify this in the official source of the relevant canton.

How can you request instalment payments if the tax cannot be paid in one lump sum?

It is advisable to request payment relief (Zahlungserleichterung) — either instalment payments or a payment extension — from the competent tax authority before the payment deadline expires. In the request, you must explain why payment in full is not possible and what repayment schedule is realistic. It is important to know that approval of instalment payments does not eliminate default interest: it continues to accrue on the remaining outstanding balance.

What should a Hungarian taxpayer living in Switzerland pay particular attention to when receiving a tax authority letter?

Letters are issued in the official language of the canton (German, French, or Italian), and the 30-day appeal deadline does not stop running while a translation is being prepared. The type of letter and the Rechtsmittelbelehrung (information on legal remedies) must therefore be identified immediately, with assistance if necessary. If the letter also concerns income or assets in Hungary, expert advice may be justified because of the application of the Hungary–Switzerland double taxation treaty.

Do the rules on instalment payments differ by canton?

Yes, significantly. In the canton of Zürich, instalment payments can be requested online, and according to an earlier draft, the maximum term is up to 5 years, with instalments of at least CHF 1000 per tax category. In the canton of Bern, the amount of Akonto (advance payment) bills can be adjusted independently via e-banking, but a separate payment relief request must be submitted for the Schlussabrechnung (final settlement). In all cases, it is advisable to check the current conditions on your own canton’s official tax website.

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