Is a 13th-month salary mandatory in Switzerland? And for temp workers (8.33 %)?

No Swiss law requires an employer to pay a 13th-month salary. It comes from a collective labour agreement or from the contract.

In temporary work, your employer is the agency. Agencies whose main activity is staff leasing are covered by the collective labour agreement for staff leasing (GAV Personalverleih / CCT Location de services, art. 2), binding for the whole sector until 31 December 2027. Its article 18 para. 2 is clear: "Employees are entitled to a 13th-month salary."

If your assignment is on a main construction site (masonry, civil engineering, roads), the agency must also apply the LMV/CN rules on salary (Employment Services Act, AVG/LSE, art. 20). The ordinance that sets out these rules expressly lists "the 13th-month salary pro rata temporis", meaning in proportion to the time worked (Employment Services Ordinance, AVV/OSE, art. 48a para. 1 let. d). Its main rules, including the 13th, have been binding for the whole sector since 1 April 2026, until 31 December 2031.

So the 13th is calculated last, on the total already increased by public holidays and holidays. That is why the percentage looks small but the amount is not.

Under the LMV/CN, the basic rule is payment at the end of the year. If the contract does not last the whole year, which is the case for most assignments, you receive 8.3% of the year's salary with the last pay (art. 46 para. 3). By written agreement, it can be paid every six months; and for workers subject to withholding tax, monthly payment can be agreed (art. 46 para. 2). In all cases, it must be shown separately on the salary statement.

Under the staff leasing agreement, the 13th-month share is included in the gross hourly wage of the official table (appendix 2). So it comes with each pay.

If you see nothing in December, it is not necessarily a mistake: look at each payslip instead, or at the last payslip of your assignment.

These are three separate rights.

In Geneva, the joint committee for the main construction sector (CPGO) set this percentage at 3.17% for 2026. The paid public holidays in Geneva in 2026 are 1 January, 3 and 6 April, 14 and 25 May, 10 September, 25 and 31 December. In the canton of Vaud, the joint professional committee for masonry and civil engineering also gives 3.17% for calendar year 2026, in its 2026 work calendar; under the LMV/CN, the joint committee's percentage is what counts (art. 34 para. 5). For Valais, ask your agency or the Valais joint committee for construction which percentage applies.

Holiday pay also follows strict rules. The LMV/CN forbids paying holiday pay in cash with the salary during the contract: it is credited on each statement and paid when you take your holidays (art. 31 para. 2). The staff leasing agreement allows it for a single assignment of three months at most, provided it appears separately on the payslip (art. 13 para. 2). For a temporary worker on a site covered by the LMV/CN, the official commentary on the staff leasing agreement is clear: holidays and their payment follow the LMV/CN, not art. 13 of the staff leasing agreement (staff leasing agreement art. 3 para. 1, AVG/LSE art. 20, AVV/OSE art. 48a). So the LMV/CN rule is what counts: holiday pay is recorded on each payslip and paid when you take your holidays.

Fictional example. Arben, 35, a skilled construction worker (class A), works 170.00 h in September 2026 for an agency, on a main construction site in Geneva. His 2026 minimum wage is CHF 32.80 per hour (LMV/CN, appendix 4). His contract pays public holidays as a percentage (LMV/CN art. 34 para. 5). The hourly shares are those of the 2026 table of the Geneva joint committee (CPGO) for temporary work:

With the September pay, Arben therefore receives CHF 5'752.80 gross (base and public holidays). The CHF 610.30 of holiday pay and the CHF 528.70 of 13th-month salary are earned, but set aside. If he is subject to withholding tax (Quellensteuer / impôt à la source), he can agree in writing with the agency to receive the 13th every month (LMV/CN art. 46 para. 2): he would then receive CHF 6'281.50 gross.

His colleague Luís, 52, same class, same site, is entitled to more holidays (13.0%). For 170.00 h, he earns a total of CHF 7'039.70 (CHF 41.41 per hour), including CHF 748.00 of holiday pay and CHF 538.90 of 13th-month salary.

These amounts are gross, before social deductions and withholding tax.

And the "all-inclusive rate"? The CPGO publishes this total of CHF 40.54 per hour as the "converted salary". It adds all the shares into a single hourly rate. But the table does not say when each share is paid, and the LMV/CN forbids paying holidays with the salary during the contract (art. 31 para. 2). If your agency pays you CHF 40.54 per hour every month, the holiday share has already been paid to you: you will not be paid a second time during your holidays. Ask your agency how it handles holidays and, if in doubt, ask the CPGO (or the joint committee of your canton) or a trade union.

• Look for a line "13th salary", "13th share", "13e salaire", "13ème mois" or "13. Monatslohn". It must be separate from the base salary (LMV/CN, art. 46 para. 2).
• Check the rate: 8.3% on an LMV/CN site, 8.33% under the staff leasing agreement.
• Check the base: the percentage must apply to the base salary plus holidays and public holidays, not only to the base salary.
• Do not confuse it with "holidays" (10.6% or 13.0% on an LMV/CN site) or with "public holidays".
• If no line appears each month, the 13th must arrive at the end of the year or with the last pay of your contract.

If the amount is not right, first ask your agency for a written explanation. Without an answer, the joint committee or a construction trade union can help you.