Start with Swiss withholding tax and AHV. It explains the deductions that can appear on a payslip, including AHV/IV/EO and unemployment insurance, and why foreign employees without a C permit are commonly taxed at source.
Then use withholding tax by canton to understand why there is no single national percentage. The competent canton, tariff code, marital status, children and other personal data can change the deduction.
Payroll also connects directly to your residence status, because the permit can change the assessment route, and to the wider Swiss tax system, because withholding is a collection mechanism rather than proof that your entire tax position is finished.
If you are moving with complex compensation, foreign assets, share plans or more than one country still in the picture, a Swiss relocation strategy consultation can identify what needs to be solved before the first Swiss payslip.