The health questionnaire is the moment a supplementary insurance policy is decided. It arrives with the application, it looks like an administrative formality, and it is the only document in the file in which one inaccurate sentence can still have consequences years later.
So it is worth knowing exactly what the law asks for — and, more surprisingly, what it does not.
Why it exists, and only on the supplementary side
Basic insurance (KVG/LAMal) asks no health questions: the insurer must accept every person required to be insured who lives within its area of operation. Supplementary insurance falls under the federal law on insurance contracts (VVG/LCA), where no such obligation exists. FINMA puts it bluntly in its fact sheet on supplementary health insurance: insurers may, at their discretion and without giving reasons, turn down an applicant for supplementary cover.
The questionnaire is the instrument of that freedom. It is used to assess a risk before deciding whether it will be taken on, and on what terms.
The duty covers the questions asked, not your whole life
This is the most misunderstood point of all. Article 4 of the VVG/LCA requires the applicant to disclose, by means of a questionnaire or in answer to any other question, the facts material to assessing the risk that they know or ought to know. The mechanism is that of an answer: there is no duty to volunteer what you were not asked.
Article 6, which governs the consequences, says the same thing from the other side: it covers only a material fact “about which they were asked”.
What makes a fact “material”
The law first sets a substantive test: material facts are those capable of influencing the insurer's decision to conclude the contract at all, or to conclude it on the agreed terms. It then adds a presumption that does all the work in practice: facts about which the insurer asked specific, unambiguous questions are deemed material.
Two consequences follow, and they point in opposite directions. A specific question brings the fact within the duty almost automatically. A vague question, by contrast, does not benefit from the presumption — and it was the insurer who wrote it.
What an inaccurate answer allows the insurer to do
The legal term is non-disclosure: having failed to disclose, or disclosed inaccurately, a material fact that was known or ought to have been, about which a question had been asked. The law does not make the contract void. It gives the insurer a right to terminate, which takes effect when the notice reaches the policyholder.
That right is subject to a short time limit: it lapses four weeks after the insurer became aware of the non-disclosure. The deadline runs from knowledge, not from signature — which explains why non-disclosure can be invoked long after the contract was concluded, if the insurer has only just learned of it.
The most expensive part is not the termination. If the contract ends this way, the insurer's obligation also lapses for claims that have already occurred, but only to the extent that the undisclosed fact influenced whether the claim occurred or how large it was. Where that influence exists, the insurer can demand repayment of what it has already paid.
Three situations in which the insurer loses this right
The law provides for cases in which termination is not available despite the non-disclosure. The three that come up most often:
- the undisclosed fact had ceased to exist before the claim;
- the insurer itself caused the non-disclosure;
- the insurer knew or ought to have known the undisclosed fact.
The third case is worth remembering. An insurer that already held the information — because it appeared in a file it was managing, for example — cannot later rely on it as an omission.
How far back can the insurer go?
The law sets no outer limit. It gives four weeks from knowledge, and stops there. Elsewhere, when the legislature wanted an absolute limit, it wrote one in: the right to terminate for breach of the insurer's duty to inform lapses at the latest two years after the breach. Nothing of the kind accompanies non-disclosure.
The figures that circulate on this point — five years in particular — come from a different regime, that of the optional daily-allowance insurance under the KVG/LAMal, and do not apply to a supplementary policy under the VVG/LCA.
Your answers are sensitive data
Health data are sensitive data within the meaning of the federal data protection law (DSG/LPD), and processing them requires express consent. In parallel, the VVG/LCA requires the insurer to inform you, before the contract is concluded, about the processing of your personal data: the purpose, the type of data file, the recipients and the retention period.
You are entitled to this information. If it is missing from the documents you are given, that is a question to ask before signing, not after.
If you do not know what to answer
There is no official guide on how to fill in a health questionnaire. Neither FINMA, nor the Federal Office of Public Health (FOPH), nor the health insurance ombudsman publishes one.
What follows from the text is more useful than general advice: put the question to the insurer and keep its answer. Since 2022 the law places the insurer's question and your communication on the same evidential footing, which gives a written exchange the same value as the form. An insurer that itself resolved your uncertainty will find it hard to call your answer non-disclosure later.
And the reverse deserves saying just as clearly: filling it in loosely to be accepted more easily achieves nothing. It does not make the fact disappear; it merely moves the moment it will come to light — usually the moment you report a claim.