Start with the ordinary documents
Most expats should begin with employment and residence basics: salary certificate, permit or residence details, marital status changes, child or dependent information, and any canton-specific tax correspondence.
Then add pension and deduction documents. A Pillar 3a contribution needs a tax certificate from the provider. Pension fund certificates, vested-benefit documents, insurance certificates, and professional expenses may also matter depending on the case.
The goal is not to become a tax expert. The goal is to make the return possible without guessing or rebuilding the year from bank notifications.
Investment and foreign asset folder
For bank and broker accounts, collect year-end statements, dividend and interest reports, transaction summaries, and any tax vouchers. Keep the source currency visible, especially if accounts are outside Switzerland.
Foreign accounts should not be treated as invisible just because they are outside the country. Swiss residents commonly need to consider worldwide income and wealth, subject to exact rules and treaty treatment.
If you hold listed securities, official tax values and income data may be relevant. ICTax is one of the tools used in the Swiss tax reporting environment, while broker statements remain the starting evidence.
Make the file useful for a person
A good folder has one subfolder per tax year and one simple index. Use labels such as salary, Pillar 3a, Swiss bank, foreign bank, broker, pension, property, insurance, and correspondence.
For each account, write the provider name, country, account number ending, year-end balance, income received, and tax withheld. This small index helps you see missing documents before the deadline.
If you are taxed at source, still keep the same folder. A later ordinary tax assessment, withholding correction, relocation, or bank review can require documents that you did not expect to need.
When the situation crosses several countries, keep copies of residence certificates, treaty correspondence, and adviser notes. Clean records do not guarantee a tax result, but they reduce avoidable confusion.