Notice period (Kündigungsfrist).
Period within which a lease must be terminated. Typically 3 months in Switzerland.
The Kündigungsfrist (notice period) in Swiss rental law is 3 months by default and can be extended by contract. Termination must be in writing; on a family-home contract it is signed by both spouses.
Termination dates: typically three dates per year in Switzerland: 31 March, 30 June, 30 September. Some cantons have different dates.
Calculation: terminate on 10 March for 30 June? OK. Terminate on 1 April for 30 June? No longer possible. You then wait until the next date, 30 September.
Early termination: you can leave any time if you propose a reasonable replacement tenant who is solvent and willing to take over on the same terms. The landlord then can't refuse them.
Family or job hardship: in hardship cases (illness, job loss, separation) you can request a deadline extension.