How long can I stay in Switzerland?

UK citizens - From 1 January 2021 (Brexit) citizens of the United Kingdom and Northern Ireland will be treated as “third-country” nationals but they are exempt from visa requirements when entering Switzerland. They are permitted to stay for up to 90 days in any 180 days period (as tourists without working).
 
Citizens of Schengen (EU) countries - Switzerland has been a member of the Schengen Area since 12 December 2008 so applies the same rules as all Schengen countries – citizens may stay for up to 90 days in any 180-day period.
 
Citizens of “Third countries” – do I need to apply for a visa?
That depends on your nationality. For stays of up to 90 days many third country nationals do not require a visa but for a full list see offical guidance.
 
Can I stay longer if I own a property in Switzerland?
Owning a property in Switzerland does not give you any additional rights to enter and stay in Switzerland for longer than 90 days.
Anyone who wants to work during his/her stay in Switzerland or to stay for longer than three months requires a permit. Residence permits are issued by the Cantonal Migration Offices. A distinction is made between short-term residence permits (less than 1 year), annual residence permits (limited) and permanent residence permits (unlimited).