How double basic insurance happens
Duplicate membership usually follows a switch that was never properly completed. The insured person signs a proposal with a new insurer effective 1 January but forgets to send the cancellation to the old fund before the 30 November deadline. As a result, two mandatory health insurance contracts coexist from the start of the year, even though the law allows only one basic cover per person.
Other situations exist: an intercantonal move, the automatic enrolment of a newborn with two funds, or an administrative error between insurers. The core issue is the same. As long as the first cancellation is not confirmed, the old fund keeps issuing monthly premiums and the new insurer bills as well. The situation must therefore be cleared up quickly to avoid arrears piling up.
Checking which of the two memberships is valid
Before taking any step, identify which cover the law recognises as effective. In principle, the old contract remains valid as long as the cancellation has not been received on time and the move to the new insurer has not been confirmed without a gap in cover. The new membership can only take effect if the old one was properly terminated under the legal notice period of one month for the year-end deadline.
Gather the documents: a copy of the signed proposal, any acknowledgement of receipt, letters from both funds and the first invoices. These documents determine the effective date that applies. If the cancellation never reached the old insurer, that insurer generally remains your legal basic insurer, and it is the new membership that will have to be cancelled.
Steps to put things right without delay
Write to both funds concerned, explaining the situation and enclosing your supporting documents. Ask the insurer whose membership is not valid to cancel the contract and stop billing. Use registered mail or the official form in your client portal so that you have dated proof of your action.
Documents to provide
Enclose proof of membership with the fund you wish to keep, because the law requires continuous cover: no fund may leave you without basic insurance. State clearly the desired effective date and your insured number. The more complete the file, the faster the duplicate cover is cancelled, which reduces the number of premiums billed in parallel.
Keep a copy of every letter and note the dates. If the two insurers disagree, these records will form the basis of your complaint and, if necessary, of a submission to the health insurance ombudsman.
Recovering premiums paid in excess
When one of the two memberships is cancelled retroactively, the premiums already paid to that insurer must in principle be refunded, less any benefits it has already covered. The refund is usually made by transfer or by offsetting against future invoices. Ask for a detailed statement to check that the period of double billing is fully neutralised.
If treatment was reimbursed by the fund whose membership is being cancelled, a compensation mechanism between insurers applies. You do not have to manage this transfer yourself, but make sure the deductible and the retention rate applied match the cover finally recognised. Written follow-up prevents amounts from wrongly remaining at your expense.
Preventing another double membership
When switching funds, the golden rule is never to cancel the old contract before you have written confirmation from the new insurer. Conversely, do not forget to send the cancellation within the one-month notice period before 30 November, for effect on 1 January. Either of these oversights is enough to create a gap in cover or, the other way round, a double membership.
Always keep the acknowledgements of receipt and check in January that you receive only one basic premium invoice. If your premium rises during the year, an extraordinary right of cancellation applies: here too, coordinate the dates to avoid any overlap. A simple checklist, applied every autumn, is enough to keep the risk of duplication away for good.
Frequently asked questions
Can I hold basic insurance with two funds at the same time?
No. The law requires only one mandatory health insurance per person. If two memberships coexist, one is invalid and must be cancelled. In practice, the membership prevails where the cancellation of the old contract was not received on time; the other one is then put right.
Who should I contact first in case of double membership?
Write to both funds at the same time, explaining the situation and enclosing your supporting documents. Ask for the invalid membership to be cancelled and its billing stopped. Registered mail or the official client-portal form gives you dated proof, useful if the insurers do not agree straight away.
Will I get back the premiums I paid twice?
In principle yes. When a membership is cancelled retroactively, the premiums paid to that insurer are refunded, less any benefits it already covered. Ask for a detailed written statement and check that the entire double-billing period is neutralised before you close the file.