How it's calculated
Typically your monthly base salary once more, pro-rated if you start or leave mid-year. It counts as ordinary salary: AHV/ALV deductions and taxes apply, and it's included in pension-relevant income.
The budgeting trap
Treating the 13th as 'free money' in December is the classic mistake. Smarter: plan the year on 12 salaries and assign the 13th in advance – tax bill, health insurance annual payment (often with a discount), pillar 3a top-up or holiday fund.
Make it visible
Add it as expected income in your budget so December doesn't distort your averages.
Track these costs in your own budget: create your free Swiss budget in BudgetHub – in English, with Swiss categories built in.
What the thirteenth salary is – and is not
It is not a bonus and not an extra month of pay in the sense of additional money for the same work. Where it exists, the annual salary is divided into thirteen parts rather than twelve, with the thirteenth typically paid in November or December. The annual total is what matters when comparing offers.
It is also not a legal entitlement in Switzerland: it exists only where the employment contract or a collective agreement provides for it. An offer of CHF 8'000 × 13 and one of CHF 8'667 × 12 are the same annual salary – the second simply pays it more evenly.
Pro-rata rules apply when joining or leaving mid-year: you are normally entitled to the proportional share, but check the contract, as some agreements condition payment on being employed at the payout date.
Why it is taxed more heavily than it feels
The thirteenth salary is ordinary income: it is subject to social contributions and income tax like any other salary component. For source-taxed employees, the month it is paid can push the monthly tariff into a higher band, which is why the net amount often disappoints.
For ordinarily assessed taxpayers there is no separate treatment either – it simply raises annual taxable income. Anyone provisioning for taxes monthly should therefore raise the provision in the month it arrives rather than treating it as free money.
Where it genuinely helps is timing: arriving in November or December, it lands close to the annual bills that break budgets – taxes, insurance, Serafe. Using it for those is unglamorous and highly effective.
A sensible allocation rule
A workable split for the net amount: the largest share to the provisions that are actually due (taxes, annual bills), a defined share to savings or pillar 3a – note that 3a contributions must be made before 31 December to count for that tax year – and a deliberate share to spending, because a rule with no enjoyment in it does not survive contact with December.
Treating the entire amount as savings sounds disciplined and usually fails. Treating it as free money fails faster. The written split, decided in advance, is what keeps it from evaporating.
If the thirteenth is your only mechanism for annual bills, that is a signal rather than a plan: it means the monthly budget is not provisioning, and a single change of employer would expose the gap.