The KVG (Health Insurance Act) stipulates that anyone who comes to Switzerland to work or registers as a resident in Switzerland must enroll in a recognized Swiss health insurance plan. If a person fails to comply, the Office of Migration will automatically enroll them in a health insurance plan.
Only cross-border commuters who have their primary residence in the following countries and can provide proof of adequate health insurance in their country of residence are eligible for an exemption:
Germany, France, Italy, Austria, Portugal (2), Spain (2)
People whose primary residence is in Liechtenstein do not need insurance in Switzerland
People from the following countries are required to have health insurance in Switzerland:
Belgium, Bulgaria, Denmark, Estonia, Finland, Greece, Great Britain, Ireland, Iceland, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal (1), Romania, Sweden, Slovakia, Slovenia, Spain (3), Czech Republic, Hungary, and Cyprus
(1) Only for cross-border commuters and the unemployed; retirees with permanent residence in Switzerland:
(2) Only retirees;
(3) Except for retirees
http://www.gebo.ch/sozialversicherungen-grenzuberschreitend/