Withholding vs declaration, the tax switch

For most new arrivals, tax is withheld directly from your salary (Quellensteuer or impôt à la source). You do nothing. But two thresholds change that.

Earn above CHF 120,000 gross per year, or hold a C permit, and you file a full tax return (ordinary assessment) instead. The employer still withholds, but you reconcile every year in April.

In some cases (mortgage interest, big pension contributions, high medical bills) filing voluntarily saves you money even below the threshold.

Deadlines: 31 March for the previous year, extendable to autumn if you file a short online request in most cantons.