Fax and banking: powers of attorney, stop payments, transfers

Short answer: a bank will not open an account on the strength of a fax and will not release a mortgage loan on a fax — but it still accepts faxes for three families of urgent instructions: written confirmation of a stop payment on a cheque or card already reported by telephone, transmission of a supporting document requested by a back-office team ahead of a deadline, and certain one-off instructions under an existing mandate (transfer to an already registered account, switching funds within a life insurance policy, release of a guarantee) where the account agreement or the mandate explicitly provides for it. Everything else — powers of attorney, changes of bank details, subscriptions, closing a savings product — requires a handwritten or electronic signature, in branch or through the customer portal. The rule to remember: a fax transmits an instruction, it does not create consent.

Why banking is a special case

In most sectors, the fax question boils down to its evidential weight. In banking, a second layer comes into play: compliance. A credit institution is bound by the French monetary and financial code to due-diligence obligations regarding the identity of its customer and the origin of funds. These obligations, enforced in France by the ACPR (Autorité de contrôle prudentiel et de résolution) and regularly restated in its guidelines, explain why an adviser will tell you "I can't process that by fax" for an operation that strikes you as entirely routine.

The logic is not arbitrary. A fax is anonymous by design: nothing in a transmission guarantees that the person who fed the sheet into the tray is in fact the account holder. The reproduced signature is an image, and perfectly easy to copy. For a bank, accepting a payment instruction on that basis alone means shouldering the risk of CEO fraud or supplier impersonation fraud — two scenarios that the Banque de France and the Observatoire de la sécurité des moyens de paiement document year after year as the most costly for businesses.

Hence the dividing line: a fax is accepted where the identity of the person giving the instruction has already been verified through another channel, and refused anywhere it would on its own constitute proof of consent.

Operations where a fax still holds up

Confirming a stop payment

This is the textbook case, and it is provided for in the legislation. A stop payment on a lost or stolen cheque, like a stop on a bank card, is first reported by telephone — urgency demands it. But article L. 131-35 of the monetary and financial code requires written confirmation of a stop payment on a cheque: without it, the telephone stop lapses after a few days and the cheque becomes payable again.

That written confirmation is not subject to any particular form. A registered letter works. So does a fax, and it carries a decisive advantage: it arrives within the minute, with a time-stamped transmission report, where registered post takes two days. Over a long weekend when the branch is closed and the stolen cheque could be presented on Monday morning, a fax to the stop-payment department or to head office solves the problem.

Two precautions: state the grounds for the stop (loss, theft, fraudulent use, insolvency proceedings against the payee — the only legally admissible grounds), and keep the transmission report together with a copy of the fax you sent.

Feeding a file that is already open

A back-office team asks you for proof of address, a tax assessment, a preliminary sale agreement, a borrower's insurance certificate. The file exists, your identity is established, only one document is missing and a deadline is approaching: this is precisely fax territory.

The constraint here is technical rather than legal. A faxed supporting document must remain legible after rasterisation. An identity document that has been photocopied and then faxed in standard mode often comes out as an illegible black block, and the department will ask for it again. A document scanner with an automatic feeder set to greyscale at 300 dpi, sending from the file rather than from the glass, gives a far cleaner result — the document leaves as a PDF and the gateway handles the conversion.

Instructions provided for by the mandate

Certain one-off instructions are admissible by fax because a previously signed document authorises it. The classic examples are a discretionary management mandate on a securities account, a corporate account agreement that provides for instructions to be sent by fax with a list of authorised signatories and specimen signatures on file, or certain life insurance policies for switching between investment funds.

The legal mechanism is simple: the framework agreement was signed in due form, it organises the channel, and the fax is merely a means of execution. Read your account agreement before faxing: if it is silent on the point, the bank will refuse without discussion.

Operations where a fax is always refused

The logic is easy to read: as soon as an operation is irreversible or creates an authority over funds, a reproduced signature is no longer enough. Insisting achieves nothing and wastes the time you thought you were saving. In those cases it is better to switch straight to the expected channel — and if timing is the issue, back it up with a fax notifying your intention, which time-stamps your move without claiming to stand in for a signature.

Confidentiality: the real risk of banking faxes

A bank statement, an amortisation schedule, a balance certificate: these are personal data of a financial nature, and they travel to a machine you cannot see. In a branch, the fax machine is often at the back of the advisers' area; at head office, in a shared department. The CNIL regularly reminds senders that they remain responsible for the data they transmit and that sending to a wrong number constitutes a data breach within the meaning of the GDPR, with an obligation to keep an internal register and, depending on severity, to inform the individuals concerned.

Four habits that cost thirty seconds:

• Check the number twice, digit by digit, reading it out loud. The numbers of banking departments often differ by a single digit between branches of the same network.
• Mask whatever is not needed. Proof of address does not need to show a full IBAN. A permanent redaction marker used on a photocopy, not on the original, settles the matter — marker on the original can often still be read through the paper.
• Announce the transmission by telephone when the document is sensitive, so that someone is waiting for it at the output tray.
• Add a cover page naming the recipient, the department, the number of pages and a confidentiality notice. It limits the damage of a wrong number and demonstrates your diligence.

If you fax from home, storage is another question. Banking documents left lying near the printer end up in the bin without being destroyed: a cross-cut shredder solves that for a few tens of euros, and it is essential as soon as you handle statements on someone else's behalf — an elderly relative under a protective mandate, a company managed remotely.

What a fax transmission report is worth against a bank

The transmission report does not prove that your instruction was valid. It proves that a specific document was sent to a specific number at a specific time, and that the machine at the other end accepted it. That is exactly what you need in a dispute about deadlines.

A judge's reasoning, under French law, starts from article 1366 of the civil code: an electronic document has the same evidential weight as a paper one provided its author can be identified and its integrity guaranteed. A fax does not tick those boxes on its own. It becomes probative through a body of corroborating evidence: the transmission report, a copy of the document sent, the acknowledgement or the department's reply, a logged telephone exchange, possibly an email confirmation in the minutes that follow. We set out this mechanism in detail in our article on the evidential value of a fax before a judge.

In practical terms, for a disputed stop payment on a cheque, a winning file looks like this:

1. The time stamp of the call to the stop-payment service (phone bill or the file number provided).
2. The copy of the confirmation fax, with the date and the grounds.
3. The transmission report showing the number dialled and the status "OK".
4. The bank's written reply, however terse.

Together, those four items tell a coherent story. In isolation, they carry no weight. That is why you should file them the same day, in the same folder, with the same file-naming convention prefixed by the date. Our recommended retention periods are set out in the article on archiving fax transmission reports: for banking matters, allow five years for anything touching on a contract or a debt, and ten years as soon as a property transaction or a guarantee is involved.

The case of credit institutions and over-indebtedness

Consumer credit companies, debt collection agencies and over-indebtedness commissions form a slightly different world. The fax survives better there, for a prosaic reason: these organisations handle considerable volumes of post and their litigation departments have kept fax lines because they produce an immediate record.

Two recurring situations.

A request for extra time or restructuring. You are replying to a formal demand running on an eight- or fifteen-day deadline. The fax brings your reply within the deadline, and the transmission report proves it. Then send the same letter by registered post: the fax secures the date, the registered letter secures the form.

An over-indebtedness application. Filing with the Banque de France over-indebtedness commission is done as a complete application, online or by post — not by fax. On the other hand, an additional document requested by the commission's secretariat can legitimately be sent by fax if the secretariat accepts it, and that is often the case when the admissibility date is at stake.

In exchanges that stretch over months, traceability is worth its weight in gold. A dedicated lever-arch file with dividers per creditor, kept in chronological order, saves you three hours hunting for proof that you did reply on 12 March. And for professionals handling several cases, an automatic date stamp applied to every incoming letter creates a reliable marker on the paper itself.

Fax, banking and alternatives: where do we stand in 2026

The question deserves to be asked plainly: can you still rely on the fax when dealing with a bank? The answer is nuanced.

French retail banks have shifted en masse to the secure messaging system in the customer portal, which has a genuine advantage over the fax: the sender is authenticated, so the instruction can be attributed. For a private customer with working online access, that is the channel to prefer, and an attachment sent that way carries more weight than a fax.

The fax regains the advantage in four configurations:

• The customer portal is inaccessible — blocked password, strong authentication device unavailable, change of phone.
• Your counterpart is not your bank but a third-party service with no portal: a notary, a litigation department, the back office of a borrower's insurer.
• You are acting on behalf of a third party under a protective mandate and have no online access to the account.
• You need to produce a self-contained record that you control, independent of a customer portal that may close or lose its history after eighteen months.

On that last point, the comparison between the two channels is developed in our article fax or secure messaging. The summary fits in one sentence: secure messaging is better at proving who wrote, the fax is better at proving when — and you come away with a file on your own hard drive.

Frequently asked questions

Can a bank refuse a fax it has duly received?

Yes, and there is no contradiction. Receipt does not amount to acceptance. If the account agreement or the regulations require an original signature or strong authentication, the bank must refuse the instruction even when it has been received and is legible. It does, however, remain obliged to inform you within a reasonable time, and the transmission report will be useful in showing that you acted in time if its silence caused you to miss a deadline.

Is a fax enough to confirm a stop payment on a cheque?

As a matter of form, yes: the law requires something in writing, without prescribing the medium. In practice, fax and send a registered letter the same day. The fax secures the date, the registered letter secures proof of receipt through an independent third party. Keep both in the same folder.

Can a banking power of attorney be granted by fax?

No. A power of attorney is an act conferring authority over someone else's funds: it requires the presence or certain identification of both the principal and the attorney, with specimen signatures collected. No French bank accepts it by fax, and rightly so.

Do you need a physical fax machine to fax your bank?

No. An online fax service sends a PDF to the recipient's fax number, which receives a perfectly standard transmission. The advantage is twofold: the document quality is better than a hurried scan, and the transmission report arrives as an archivable PDF. The list of covered destinations can be found on the available countries page.

How long should banking fax reports be kept?

Five years for anything relating to a contract, a debt or a civil obligation. Ten years for documents linked to a mortgage loan, a guarantee or an accounting operation. One year is enough for routine transmissions with nothing at stake. When in doubt, keep them: a PDF weighs a few hundred kilobytes.

In summary

• A fax remains admissible to a bank for confirming a stop payment, completing an open file or carrying out an instruction provided for by a signed mandate.
• It is always refused for opening an account, granting a power of attorney, changing the IBAN of a recurring transfer, closing an account and releasing funds.
• A transmission report does not prove the validity of the instruction: it proves the date and the sending. Its strength comes from the body of evidence — document sent, report, the department's reply, the context.
• Check the number twice, mask unnecessary data, attach a cover page: a wrong number on a bank statement is a data breach within the meaning of the GDPR.
• For a private customer with a working customer portal, secure messaging comes first. The fax becomes the right tool again when access is blocked, when your counterpart has no portal, or when a deadline runs out within the hour.
• Archive the same day, five years by default, ten years for property and accounting matters.