Preparing your Swiss tax return: the simple method

The tax return comes back every year. Making it simple depends less on the tax logic itself than on organising your documents: having every certificate, statement and bank record in the right place, at the right time. This guide covers what to gather, the deadlines to watch and the mistakes that cost the most.

At a glance

In Switzerland, each canton runs its own tax return: deadlines, forms and platforms vary by the canton you live in.
A deadline extension is usually granted on request, free of charge or for a token fee depending on the canton.
The useful documents fall into four families: income, wealth, deductions, personal situation.
Preparing your file in advance saves time and reduces the risk of forgetting deductions.

What you need to understand

Tax applies at three levels: federal, cantonal and communal. A single return covers all three, but it's your cantonal tax administration that runs the process. The rules differ from canton to canton (deadlines, forms, accepted supporting documents). Always check the website of your cantonal administration.

The return covers the previous year. In 2026, you declare your income and wealth as of 31 December 2025. The tax authority then issues a tax assessment, which may arrive several months later.

A few useful pointers:

The Federal Tax Administration (FTA) publishes federal rates and official documentation.
The ch.ch portal on the tax return links to the cantonal sites.
If your situation is simple (one employer, no significant wealth, no property), the return usually fits into one evening.

What to do

A four-step method:

Identify your canton's deadline (often end of March or end of April, sometimes later).
Request a deadline extension if needed: most cantons grant one online, no justification required.
Gather the documents below into a single dossier.
Fill out the return via your canton's software or online portal.

If you work with a trustee, step 3 is the most important: a clean dossier reduces the hours they'll bill you.

Useful documents

Income

Salary certificate from each employer. Official format on ch.ch · Salary certificate.
Pension statements: AHV, IV, BVG, withdrawals from the 3rd pillar.
Compensation: unemployment insurance, loss of earnings, accident insurance.
Side income: fees, self-employed activity, rental income.

Wealth as of 31 December

Bank statements (current account, savings, e-banking).
Tax statement for your 3rd pillar (3a) and voluntary BVG holdings.
Value of securities, funds, ETFs, crypto-assets.
Tax value of your vehicle (if requested by your canton).
Value of any properties in Switzerland or abroad.

Common deductions

Health insurance premiums (LAMal/KVG + supplementary).
Unreimbursed medical expenses (above a threshold).
Commuting costs between home and work.
Meal costs outside the home for work.
Continuing education tied to your employment.
Union or political party contributions.
3a contributions (up to the annual cap published by the FTA).
Alimony paid.
Donations to recognised charitable organisations.

Personal situation

Marital status as of 31 December.
Family situation (dependent children, shared custody, etc.).
Childcare receipts (daycare, after-school programmes).

Important deadlines

Standard deadline: varies by canton. Check the exact date on your cantonal tax administration's website.
Extension: generally granted on a simple online request, until autumn of the following year. Some cantons charge a few francs beyond a certain deadline.
Tax assessment: can arrive several months to over a year after submission. Once received, the legal deadline to file an objection is 30 days.
Payment: depending on your canton, payment in several instalments, discount for early payment, or a refund if your instalments exceeded the tax owed.

Common mistakes

Waiting to gather documents: most certificates arrive between January and March, but they don't sort themselves.
Forgetting legitimate deductions: unreimbursed medical expenses, continuing education, donations. That directly translates to higher tax.
Mixing up years: you declare the previous year. A salary certificate from the current year doesn't belong in the current return.
Not archiving: tax documents must be kept for at least 10 years.
Missing the objection deadline: without an objection within 30 days, the tax assessment becomes final.

Where to find official information

ch.ch · Tax return (with links to cantons)
ch.ch · Cantonal and communal tax
ch.ch · Salary certificate
Federal Tax Administration (FTA)
Official site of your cantonal tax administration (search "taxes" + your canton's name).

How Admini helps

Admini saves you the yearly document hunt:

Centralise salary certificates, 3a statements, insurance premiums and bank statements in one place.
Find a past year's document in seconds when your trustee asks for it.
Prepare a clean tax dossier to share with your trustee, partner, or just your future self next year.
Get reminders for the tax deadlines of your canton.

The point isn't to replace your trustee or your cantonal software, but to stop chasing your own paperwork.