Fax and the CPAM: Filing a Claim Without Losing Your Rights

Short answer: when dealing with a primary health insurance fund (CPAM), an MDPH disability office or a medical review service, fax remains useful in one specific situation: when the clock is ticking and you need to prove the date of dispatch. The sick leave certificate due within 48 hours, the internal appeal to be filed within two months, the supporting document requested before a file is closed. The time-stamped, page-by-page transmission report then serves as prima facie written evidence — something that neither an upload to an online account without acknowledgement, nor a simple email, can always guarantee. That said, fax does not replace the official channels: it backs them up. The right method is to use the prescribed channel (ameli account, official form, registered letter) and to secure the date with a traceable transmission when the deadline is tight.

Why health bodies never cut the line

France's Assurance Maladie has digitised heavily: electronic claims via the Vitale card, paperless sick leave notices (online AAT), workplace accident declarations through net-entreprises, the ameli account for policyholders. On paper, the fax machine has no place left.

In practice, the administrative departments of the funds, the medical review services, the départemental MDPH offices, the health screening centres and the MSA funds all still print fax numbers on their letters and forms. There are three reasons for this.

The first is structural: not every sender is connected. A locum doctor without approved software, a practitioner abroad, an employer with no net-entreprises access, a facility with a downed information system — all still produce paper. That paper has to arrive somewhere.

The second concerns exceptional flows: documents urgently requested by a medical adviser, a missing supporting item on a stalled file, a corrected salary statement. None of these exchanges fit into an online form.

The third, and the most decisive for you, is evidentiary. When a right is about to lapse, the question is no longer "did the document arrive?" but "on what date did it leave?". On that ground, a fax transmission report is a dated, detailed and verifiable item, showing the number dialled, the time, the duration, the page count and the identifier of the remote fax machine. We covered this status in detail in our article on the evidential value of fax before a judge.

The deadlines that show no mercy

Before choosing a channel, you need to know the deadline. Here are the main time limits faced by policyholders and professionals, as published by the Assurance Maladie on ameli.fr and by service-public.fr.

These deadlines share one characteristic: they are counted in days, not weeks. An ordinary letter posted on a Friday evening sometimes arrives the following Wednesday. A registered letter costs you time at the counter. A fax transmission, by contrast, is dated to the minute.

Rule of thumb: the shorter the deadline, the more proof of date outweighs the convenience of the channel.

What you can reasonably send by fax

Not every document lends itself to faxing. Black-and-white rasterisation at 204 × 196 dots per inch, the Group 3 standard, crushes shades of grey and destroys photographs. Sorting is therefore done by document type.

Come through very well: completed Cerfa forms, salary statements, typed medical certificates, letters of objection, bank details (RIB), proof of address, printed prescriptions.

Come through badly or not at all: imaging films, ID photographs, documents marked with fluorescent highlighter (yellow disappears, pink turns black), pencil handwriting, forms printed in pale grey, iPhone scans cropped at an angle.

For handwritten items — and medical certificates often are — running them through a compact flatbed scanner first produces a far more legible file than a smartphone photo: the page is lit evenly, the contrast is stable, the stamps remain identifiable. It is a detail, but an illegible certificate is a returned certificate, and a returned certificate means two weeks lost.

A word of method: never fax a document without first reviewing it at 100% on screen. Half of all rejections stem from an unticked box, an incomplete social security number or a missing signature — not from transmission quality.

The five-step method

1. Identify the right recipient

A CPAM is not a single counter. The administrative department, the medical service (medical advisers), the internal appeals board and the cash benefits department have separate addresses and sometimes separate numbers. The fax number that matters is the one printed on the most recent letter you received, not one found in a general directory. If the letter mentions none, call 36 46 and explicitly ask for the fax number of the relevant department, noting the agent's name and the time of the call.

For the MDPH offices, each département has its own set-up. Some accept faxes for supporting documents but require the original Cerfa form 15692 by post. Check on your departmental council's website.

2. Build a self-contained transmission

A fax arrives with no envelope, no obvious sender, sometimes into a tray shared by several departments. It must therefore carry its own context. A cover sheet is mandatory, including:

• your surname, first name, date of birth;
• your full social security number, including the check key;
• the file reference or the reference of the letter you are answering;
• the recipient department spelled out in full;
• the total number of pages, cover sheet included;
• a telephone number and a return address.

That cover sheet is what separates a processed file from an orphaned one. The funds receive anonymous faxes every day that end up waiting indefinitely.

3. Check legibility before sending

Open the PDF, zoom to 200%, read the digits. Characters below 9 points come through poorly. Tables with grey shading fill in. If the source document is pale, increase the contrast at the scanning stage rather than relying on the gateway.

4. Send, then keep the report

The transmission report is the only thing you will still have six months from now. It should be kept as a PDF, named meaningfully (2026-09-25_CPAM_recours-CRA_3p.pdf) and backed up somewhere other than the working computer alone. An encrypted external hard drive or an offline encrypted backup is the simplest solution for an individual and a practice alike: health files have no business on an unmanaged consumer cloud.

5. Back it up with the official channel

Fax secures the date; it does not exempt you from filing properly. Also upload the document to your ameli account, or send the original by tracked mail the same day, stating at the top: "Document already transmitted by fax on [date] at [time] to [number]". This wording links the two dispatches and prevents duplicate processing from becoming a ground for rejection.

Health data: what transmission commits you to

A sick leave certificate names a condition. An MDPH certificate describes a disability. A hospital discharge summary is a concentrate of sensitive data within the meaning of Article 9 of the GDPR. The CNIL and the ASIP/Agence du Numérique en Santé regularly stress that such documents require a heightened level of protection.

In practice, this entails three precautions.

Double-checking the number. One transposed digit sends a medical file to a stranger. On this point, our article on a fax sent to the wrong number sets out what to do within 72 hours, including the question of data breach notification.

Encrypting storage. Received files and transmission reports must be stored on a protected medium. In a practice, a security cabinet for confidential documents remains the indispensable physical counterpart to logical encryption, for paper originals that cannot be destroyed immediately.

Destroying intermediate copies. Working printouts, drafts and botched cover sheets do not go in the wastepaper basket. A cross-cut shredder rated P-4 is the minimum for documents containing a social security number. It is also what the CNIL recommends in its practical guidance on premises security.

One fundamental caveat: fax is not end-to-end encrypted. On the legacy switched telephone network it travelled in the clear; today it passes through IP gateways. Its advantage was never cryptographic confidentiality, but compartmentalisation: no shared inbox, no automatic forwarding, no attachment spreading through a reply chain. Where confidentiality is paramount, the secure health messaging system (MSSanté) remains the reference channel between professionals, as we compared in fax or secure messaging.

The special case of the internal appeal

This is the scenario where fax proves most valuable. You receive a notice of refusal — refusal of daily allowances, refusal to cover a procedure, a disputed disability rating. You have two months to refer the matter to the internal appeals board (CRA), a deadline stated in the notice itself.

The letter of referral must be reasoned, dated, signed, and accompanied by a copy of the contested decision. It is conventionally sent by registered letter with acknowledgement of receipt. But if you realise on the last usable day that the deadline is expiring, the post office is closed and the CRA does not sit the next day: a fax sent at 11:12 p.m. is dated that same day.

Two precautions then apply:

1. Send the registered letter the following morning, enclosing the transmission report.
2. In the letter, state on the first line: "Appeal transmitted by fax on [date] at [time], confirmed by the present registered letter".

Social security case law is consistent on one point: what counts is the date of dispatch, not the date of receipt, and the policyholder must be able to demonstrate it. A transmission report, an electronic acknowledgement and a confirmation letter together form a body of evidence that is hard to challenge.

For bulky files — expert reports, medical summaries, years of supporting documents — building an indexed physical binder remains formidably effective. A lever arch archive binder with numbered dividers lets you find in ten seconds the document the CRA asks for during the hearing. Simple tools outlive software reorganisations.

The costliest mistakes

Sending without a cover sheet. The file arrives, but attached to no one. It waits, then it is destroyed.

Faxing a unique original without a copy. A fax is only an image: always keep the original paper, especially for documents with the status of originals (the initial medical certificate for a workplace accident, a signed Cerfa form).

Confusing proof of sending with proof of receipt. The report proves that the remote fax machine responded and accepted the pages. It does not prove that an officer read the document. That nuance is precisely the one judges apply: prima facie evidence, not conclusive proof.

Using an old number. Funds merge, departments move, numbers are reassigned. A number found in a 2019 letter may today ring at a private company — with the GDPR consequences that implies.

Neglecting the format. Sending 30 pages at fine resolution can take more than ten minutes and fail on a dropped line. Split into batches of 10 to 15 pages, number each batch ("1/3", "2/3") and keep all three reports.

Frequently asked questions

Does the CPAM officially accept documents by fax?

There is no single national rule. Each fund organises its own inbound channels: some publish a fax number on their letters, others direct you exclusively to the ameli account and postal mail. Best practice is therefore to treat fax as a channel for securing the date, backed up by the official channel indicated on the notice you received.

My sick leave certificate is paperless — do I still have to send anything?

If your doctor issued the sick leave notice online, the parts intended for the Assurance Maladie are transmitted directly: you only have to hand over the employer's part. It is when the certificate is on paper — a doctor without software, a consultation abroad, a system outage — that the 48-hour deadline falls to you personally.

Is a transmission report enough before the social division of the court?

It constitutes serious evidence, particularly when corroborated by another indication: an electronic acknowledgement from the provider, a copy of the document sent, a confirmation letter. On its own and in isolation, it remains subject to the judge's assessment. The rule is simple: never rest a limitation date on a single document.

Can I fax a complete MDPH application?

Rarely. Cerfa form 15692 and medical certificate Cerfa 15695 are generally required as originals, with handwritten signatures. Fax is suited to supporting documents requested during processing: proof of address, attestations, ID, follow-up letters.

How long should transmission reports be kept?

Align with the limitation period applicable to the right concerned: two years for treatment forms, two years for actions to claim benefits, longer for workplace accident and occupational disease files, where cases are sometimes reopened years later. Five years is a prudent minimum, ten years for AT/MP files.

In summary

• Fax is not the main channel when dealing with a CPAM or an MDPH: it is a safety net for the date when a deadline is tight.
• Critical deadlines are counted in hours (48 h for a sick leave certificate) or weeks (2 months for an internal appeal): that is where proof of dispatch gains its value.
• A complete cover sheet, with the social security number and file reference, determines whether the document is matched to your file.
• Every transmission must be backed up through the official channel, with an explicit mention of the fax already sent.
• Health documents call for double-checking the number, encrypted storage and secure destruction of copies.
• Keep transmission reports for at least five years, ten years for workplace accidents.
• Check the fax number on the most recent letter received, never in an old directory — and see our FAQ for questions about formats and coverage.