Switzerland's tax system is complex because taxes are levied at three levels: federal, cantonal, and communal. The canton you live in significantly affects your total tax bill.
Quellensteuer (withholding tax)
B-permit holders and most non-EU permit holders pay tax at source (Quellensteuer) — automatically deducted from salary by the employer. You don't file a full return unless your annual income exceeds CHF 120,000.
Standard tax return
C-permit holders and self-employed people file a full tax return, due in March/April each year (varies by canton). You declare all worldwide income and assets.
Tax return deadline
The standard deadline is 31 March, but you can apply for an extension (usually granted until 30 September or longer with a tax advisor). File online using the cantonal tax software (e.g. TaxMe in Zurich, GeTax in Geneva).
Key deductions
Common deductions include: commuting costs (up to CHF 3,000), professional development costs, Pillar 3a contributions, childcare costs, and pension contributions.