Mutuelle and complementary health insurance fraud: forms, figures and detection

In brief: fraud against complementary health insurance accounted for 112 million euros detected in 2025, up 11.8 % in a year, with 53 % on optical care alone. Its defining feature is structural: with tiers payant (direct third-party payment, where the insurer pays the provider rather than the patient) and the 100 % santé scheme (fully covered baskets of optical, dental and hearing care), the complementary insurer pays the larger share of the expense without ever seeing the care file. The loi du 25 juin 2026 (the law of 25 June 2026) finally opens up data sharing in both directions with the Assurance maladie (France's compulsory health insurance scheme), but the Conseil constitutionnel (France's constitutional court) struck down part of it and the implementing decrees have still not been published. In the meantime, the only lever of control left is the supporting document itself.

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Mutuelle fraud: what exactly are we talking about

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Two scopes are often confused and need to be told apart.

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Fraud against the Assurance maladie obligatoire, the compulsory health insurance scheme, targets the régime général (the general scheme). It is detected and quantified by the Caisse nationale d'assurance maladie (the national health insurance fund), which holds the care data, the procedure codes and the means to audit healthcare professionals.

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Fraud against complementary health insurance targets the organismes complémentaires d'assurance maladie, the OCAM (complementary health insurance bodies): mutuelles (non-profit mutual insurers), provident institutions and insurance companies. That is the subject of this article. It bears on the share of the expense not covered by the compulsory scheme, and it follows a very different detection logic, because the complementary insurer sees neither the care, nor the medical file, nor, most of the time, the professional.

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This asymmetry is not an organisational detail. It is the primary cause of the phenomenon.

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The figures on complementary health insurance fraud

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The Association de lutte contre la fraude à l'assurance, ALFA (the French insurance anti-fraud association), publishes each year the results reported by its members. The report covering 2025 was published on 9 July 2026.

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• 946.3 million euros of fraud detected across all lines of business, up 4.9 % in a year.
• 112 million euros in complementary health insurance, up 11.8 %.
• 182 million euros in prévoyance (personal protection insurance), up by more than 25 %.
• A fraud rate of 1.27 % relative to benefits paid, across all scopes.

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Within the 112 million euros of the health line, the breakdown is highly concentrated:

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• Optical: 53 %, more than half on its own.
• Other healthcare professionals: 21 %.
• Dental: 15 %.
• Hearing aids: 8 %.
• Healthcare establishments: 3 %.

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Two cautions apply when reading these figures, and they matter more than the figures themselves.

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These are amounts detected and reported, not amounts committed. ALFA aggregates whatever its members are willing to report. An insurer that detects poorly reports little, which pulls the total down without fraud having receded. The real phenomenon is therefore structurally underestimated.

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The amounts per line of business do not add up to a consistent total from one publication to the next. Reporting scopes vary between members and between years. These figures should be read as orders of magnitude and trends, not as accounts.

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For an overview of the phenomenon across every insurance line, see our article on the figures and types of insurance fraud.

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On the compulsory scheme side, detection is advancing fast

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The comparison is useful, because it shows what access to care data produces.

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The Assurance maladie detected 723 million euros of fraud in 2025, after 628 million euros in 2024 and 466 million euros in 2023. That is a rise of 15 % over the last year and of 35 % over the one before.

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Two lessons follow.

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Fraud is mostly professional in value terms. Around 70 % of the amounts detected in 2024 came from healthcare professionals or from identity theft. Policyholders file more than half of the fraudulent claims, but account for a small share of the sums. In other words: a great many small policyholder claims, and a few professional cases that carry real weight.

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The hearing aid sector tipped over in a single year. The amounts detected there rose from 21 million euros in 2023 to 115 million euros in 2024. Fraud was not multiplied by more than 5 in twelve months; what happened is that controls were finally turned onto a sector the 100 % santé reform had made worth defrauding.

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Finally, a mission report commissioned by a letter dated 19 May 2025 and published on 20 August 2026 estimates that the fraud detected in 2024 represented only between 17 % and 23 % of the fraud actually committed. Applying that order of magnitude, real fraud against the compulsory scheme sits between 2.7 and 3.7 billion euros.

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Why complementary insurers are structurally exposed

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The vulnerability of the OCAM stems from three mechanisms that compound one another, all of which were created for good reasons.

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Tiers payant removes the policyholder's natural control. When the policyholder does not pay up front, they do not look at the invoice. A fictitious or inflated line item meets nobody to challenge it.

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The 100 % santé scheme shifted the centre of gravity of funding towards the complementary insurer. On a class 1 hearing aid capped at 950 euros per ear, the Sécurité sociale (French social security) covers around 240 euros and the complementary insurer the remaining 710 euros, close to three quarters of the price. The body that pays the most is the one that checks the least.

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The OCAM has no access to care data. Until June 2026, the code de la sécurité sociale (the French social security code) organised only a downward flow, from the Assurance maladie to complementary insurers, and only at the moment a control was triggered. Nothing on the results, nothing on the judicial follow-up. The Assurance maladie itself sometimes struggled to identify which bodies a given case concerned.

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The result: the complementary insurer settles an expense for which it knows neither the care, nor the practitioner, nor the history, on the sole strength of a supporting document received as an attachment.

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The concrete forms of fraud

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Almost all of them are document-based, and that is what makes them detectable.

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• Fake optician invoices. Frames and lenses invoiced but never supplied, or supplied in a range far below the one invoiced.
• Fake Sécurité sociale benefit statements. A fabricated or altered statement is used to justify a complementary share that has no reason to exist.
• Altered supporting documents. The invoice is genuine to begin with, but the amount, the date or the beneficiary has been retouched.
• Fictitious procedures. The service never took place. Common for procedures that are hard to evidence after the fact.
• Deliberately inflated amounts. The service exists, but its price has been marked up to soak up the cover ceiling.
• Falsified prescriptions. A prescription fabricated or recycled in order to create an entitlement to reimbursement.
• Identity theft. Use of a third party's entitlements, sometimes with their complicity, sometimes without their knowledge.
• Organised networks. A professional or an intermediary industrialises the method across hundreds of claims. That is where the amounts concentrate.

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In the ALFA reports, document fraud is by far the leading method in health insurance, ahead of every other modus operandi. Operationally, that is good news: a falsified document leaves technical traces that an automated check knows how to pick up, whereas purely behavioural fraud is far harder to establish.

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What the law of 25 June 2026 changes

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Loi n° 2026-534 du 25 juin 2026 relative à la lutte contre les fraudes sociales et fiscales (the law of 25 June 2026 on combating social security and tax fraud), at its article 21, lifts the main lock. It came into force on 27 June 2026.

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Sharing becomes two-way. The Assurance maladie and complementary insurers may now exchange information in both directions where the facts are liable to constitute social security fraud and where the seriousness or the nature of the suspicions warrants it. An OCAM can report an anomaly on the basis of article L. 114-9-1 of the code de la sécurité sociale.

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The scope of the data is strictly bounded. The OCAM may process health data on the basis of article 9.2.h of the GDPR, for reimbursement and tiers payant, for checking compliance with contracts, and for the exercise or defence of legal claims. Data attached to a diagnosed pathology code is accessible only to healthcare professionals and to the control staff placed under their authority. The data must be stored exclusively within the European Economic Area, and it is deleted as soon as the suspicion is lifted.

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The prohibited uses are named. This data may not be used for commercial purposes, for pricing, for segmentation or for actuarial assessment. The legislator has locked down the obvious risk: that the fight against fraud should serve as a Trojan horse for risk selection.

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The constitutional censure and the missing decrees

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Two important reservations prevent the matter from being treated as settled.

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The Conseil constitutionnel struck down part of the scheme. By its décision n° 2026-904 DC du 18 juin 2026 (decision of 18 June 2026), it declared contrary to the Constitution the penultimate subparagraph of 1° of paragraph III of article 21, which authorised the use of an intermediary to store and process this health data. The grounds are precise: the legislator had defined neither the identity of that intermediary, nor the categories of data it could have accessed, nor its professional secrecy obligations. Absent those safeguards, the balance struck between the right to respect for private life and the objective of combating fraud was not an even one. The rest of the article was upheld.

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The implementing decrees have not been published. The scheme refers to a décret en Conseil d'État (a decree issued after review by the Conseil d'État, France's supreme administrative court), taken after an opinion from the CNIL (the French data protection authority), to set the categories of data, the retention periods and the arrangements for informing the persons concerned. The fraud component additionally requires an opinion from UNCAM (the national union of health insurance funds). To date, these texts are still awaited, and several professional organisations are keeping up the pressure for them to be published.

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Practical consequence: the new sharing framework is not yet operational. A complementary insurer settling a claim today is in exactly the position it was in before the law. The only element it controls remains the supporting document it is sent.

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How to detect without slowing reimbursement down

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The point is not to check every claim, which would degrade the service given to the vast majority of policyholders acting in good faith. It is to concentrate the controls where the risk sits, following a proportionate risk-based approach.

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Check the document, not just that it is there. An optician's invoice, a Sécurité sociale benefit statement or a prescription can be checked automatically: internal consistency of amounts and dates, detection of retouching traces, compliance with the issuer's format, detection of a document already submitted under another reference. That is the core of automated document verification.

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Check the money trail. Verifying that the reimbursement IBAN does correspond to the declared beneficiary, and detecting an IBAN that reappears across claims with no connection to one another, rules out part of the organised networks before payment is made.

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Score the claim rather than sorting by hand. A fraud score combined with identity verification lets consistent claims through without friction and escalates to a case handler only those that accumulate weak signals.

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Document every decision. A refusal to reimburse can be contested. An audit trail retracing the controls performed and the grounds for escalation is what makes the decision defensible, before the policyholder as much as before a judge.

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In conclusion

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Complementary health insurance fraud is not set apart from other fraud by its sophistication: it is overwhelmingly document-based, and more than half of it is concentrated on optical care. What sets it apart is its information asymmetry. The main payer is the least well informed.

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The law of 25 June 2026 corrects that asymmetry on paper, but the partial censure of 18 June 2026 and the absence of implementing decrees leave the scheme inoperative to this day. Until they arrive, and in all likelihood beyond, checking the supporting document remains the most solid foothold a complementary insurer has. It has the advantage of being the only one nobody can take away from it.

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FAQ

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What is the difference between Assurance maladie fraud and mutuelle fraud?

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Assurance maladie fraud targets the compulsory scheme, which holds the care data and the means to audit healthcare professionals. Mutuelle fraud targets the share covered by the complementary insurer, which sees neither the care nor the medical file and can rely only on the supporting documents it is sent. The amounts detected are of a very different order of magnitude: 723 million euros for the Assurance maladie in 2025, against 112 million euros for complementary health insurance as a whole.

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How much does complementary health insurance fraud cost in France?

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112 million euros of fraud were detected in complementary health insurance in 2025, up 11.8 % in a year, according to the ALFA report published on 9 July 2026. That amount corresponds to what the member bodies detected and reported, not to the fraud actually committed, which is necessarily higher.

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Which type of care is defrauded the most in complementary health insurance?

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Optical care, with 53 % of the fraud amounts detected in health insurance in 2025. Next come other healthcare professionals with 21 %, dental care with 15 %, hearing aids with 8 % and healthcare establishments with 3 %.

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Can the Assurance maladie pass data to mutuelles?

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Since loi n° 2026-534 du 25 juin 2026, sharing is provided for in both directions where the facts are liable to constitute social security fraud. The data shared is limited to the nature of the procedures and services, with no diagnosis, and may not be used for pricing, for segmentation or for actuarial assessment. The scheme is not yet operational, however, for want of implementing decrees.

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What did the Conseil constitutionnel strike down in the law of 25 June 2026?

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By décision n° 2026-904 DC du 18 juin 2026, it struck down the penultimate subparagraph of 1° of paragraph III of article 21, which allowed the storage and processing of this health data to be entrusted to an intermediary. The legislator had specified neither the identity of that intermediary, nor the data it could access, nor its professional secrecy obligations. The rest of the article was upheld.

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How can a complementary insurer detect a fake invoice?

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Through an automated check of the document before reimbursement: consistency of amounts and dates, detection of traces of alteration, compliance with the issuer's format, detection of a document already submitted. That check combines with verifying that the reimbursement IBAN does correspond to the beneficiary, and with a risk score that reserves human review for the claims accumulating several signals.

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Who defrauds the most, policyholders or healthcare professionals?

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Policyholders file more than half of the fraudulent claims, but healthcare professionals and identity theft accounted for around 70 % of the amounts detected in 2024 by the Assurance maladie. A great many small claims on one side, a few heavy cases on the other.

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Sources: 2025 annual report of the Association de lutte contre la fraude à l'assurance, published on 9 July 2026; annual anti-fraud reports of the Caisse nationale d'assurance maladie; loi n° 2026-534 du 25 juin 2026 relative à la lutte contre les fraudes sociales et fiscales; décision n° 2026-904 DC du 18 juin 2026 of the Conseil constitutionnel; mission report on combating social security fraud published on 20 August 2026.