If you are employed in Switzerland and have a Permit B (not a «C» settlement permit) you are liable for taxation at source (Quellensteuer), which is deducted directly from the salary by the employer at a standard rate depending on your income.

However, if the annual income exceeds CHF 120,000 then a tax declaration is to be completed and returned to the Tax Office. This is automatically sent out to the people concerned. For further information see Quellensteuer - German