Fax and your accountant: sending documents and tax returns

Short answer: your accountant will never ask you to fax a balance sheet — they have a client portal, a digital vault and a banking API. But three times a year, fax remains the only channel that works: when a single supporting document has to go to a third party with neither a portal nor a published email address (a court registry, a debt collection department, a paid-leave fund), when a deadline expires that very evening and the platform is overloaded, and when a bank or a landlord still insists on a submission to its fax number to validate a file. Three rules to remember: fax transmits an image of the document, never the accounting original, which remains subject to retention obligations; the transmission report proves nothing unless you archive it together with an exact copy of the pages; and no document containing bank details or payroll data should go out without a cover sheet and number verification.

What fax does — and doesn't do — in an accounting workflow

The costliest misunderstanding is believing that a faxed document "exists" in accounting terms. It doesn't. It is transmitted, which is something else entirely.

The original stays where it is. Article L.123-22 of the French Commercial Code requires accounting records and supporting documents to be kept for ten years from the close of the financial year. A paper supplier invoice faxed to your firm does not become an enforceable digitised document: the copy received by the firm is a working medium, and the paper original continues to bind you. For a digital copy to genuinely replace an original, the conditions of the order of 22 March 2017 on the reliable digitisation of paper invoices must be met — timestamping, hash, compliant PDF format, storage in non-modifiable form. A fax ticks none of these boxes.

Transmission, on the other hand, can be proven. That is the whole point of the channel. An online fax transmission report shows the number called, the date, the time, the number of pages and the status. Combined with an exact copy of the pages sent, it constitutes prima facie written evidence within the meaning of article 1362 of the French Civil Code, which a judge will assess at their discretion. That is exactly what this channel is for: dating and materialising a transmission, not manufacturing an original.

Confidentiality is not automatic. A tax return package, a payroll journal, a bank statement: these are sensitive economic data and, in the case of payroll, personal data within the meaning of the GDPR. Fax carries them without end-to-end encryption over the legacy portion of the network. Good practice comes down to two actions: check the number character by character, and limit the transmission to strictly necessary documents.

The three times of year when fax becomes useful again

1. Year-end close and filing of annual accounts

For a company whose financial year matches the calendar year, the approval meeting must be held by 30 June at the latest, and filing with the commercial court registry takes place within the following month — two months if filed electronically via the one-stop business formalities portal managed by INPI. In practice, the 2025-2026 outages of the one-stop portal have taught firms to keep a fallback route.

Fax is not a filing route: you do not file annual accounts by fax. It does, however, serve to unblock a case: sending the registry a missing certificate, responding to a letter of observation, transmitting a signed power of attorney. Note the fax number of the relevant registry once and for all in your permanent file — a simple lever arch file with dividers for the permanent file beats a sticky note on your screen.

2. The spring tax return package campaign

The tax return package must be filed electronically via EDI-TDFC or the professional area of impots.gouv.fr. Nobody faxes a form 2050. But around the package orbit documents that circulate poorly: a tax compliance certificate requested by a client, proof of a tax credit demanded by an organisation, a statement of position for a financing application. When the department on the other end publishes a fax number and no named email address, the channel becomes the shortest route again.

3. Financing applications and bank requests

This is the most frequent case. A bank, a mutual guarantee organisation, a commercial landlord or a credit insurer requests a set of documents: latest accounts, forecast, company registration extract, accountant's certificate. Many of these processes retain fax reception because it lands straight in an identified processing tray, with no spam filter and no attachment size limit.

Preparing an accounting document for transmission: the five-point method

A botched accounting fax costs more than a fax never sent, because it creates false certainty. Here is the sequence that avoids nasty surprises.

1. Scan cleanly. Fax converts everything to black and white at low resolution. A table of figures scanned crooked or with too little contrast comes out illegible at the other end, and an illegible figure is worth zero. A duplex scanner with an automatic document feeder radically improves the quality of multi-page bundles and prevents skipped pages. Failing that, frame carefully, in A4, at 200 dpi minimum, and proofread the file before sending. On this point, our guide to digitising paper documents without losing their value details the settings.

2. Redact what shouldn't circulate. A bank statement sent to justify a single receipt does not need to show every transaction of the month. Redacting is not cheating: it applies the GDPR principle of data minimisation. Use a PDF redaction tool, or an annotated paper copy that you then rescan.

3. Cover sheet is mandatory. Sender's name, company name, registration number, named recipient, precise subject ("Additional documents — file no. X — financial year 2025"), total number of pages, and a confidentiality notice asking for destruction in the event of misdelivery. That is what protects you if the number is wrong.

4. Check the number twice. A transposed digit is incident no. 1. Dial it, reread it, compare it against the official source — not against an email from 2019.

5. Archive the triptych. Exact copy of the pages + transmission report + record of the send in your tool. All three together, in the same folder, named with the date. Separately, they are worth almost nothing.

The engagement letter, the blind spot

The French institute of chartered accountants requires a written engagement letter defining the scope of work, each party's obligations and the arrangements for exchanges. Reread yours: it often specifies the official channel for transmitting documents. If it designates the client portal as the sole route, a document sent by fax and not uploaded to the portal may be considered not transmitted — and the delay will be attributed to you, not to the firm.

The workaround is simple and practised in every serious firm: fax duplicates the official channel, it does not replace it. You fax to meet a deadline, then upload to the portal to meet the engagement terms. Both records exist, and they reinforce each other.

One point often overlooked: responsibility for the document received. Your accountant does not guarantee the authenticity of an invoice you send them. Their accounts preparation engagement rests on the documents you provide. A blurry faxed image, transcribed in good faith, does not expose them — it exposes you, in the event of an audit.

Confidentiality: what's really at stake with an accounting fax

Three categories of information deserve particular vigilance.

Bank details. The company's bank account details sent by fax in a financing file are a prime target for supplier fraud. Never fax bank details on their own in reply to a request received by email: call the recipient on a number you know before sending anything.

Payroll data. Named salaries, sick leave, wage garnishments: these are personal data, some of which relate to health. The CNIL regularly reminds organisations that their transmission must be limited to authorised recipients. A shared reception tray in an open-plan office is not an authorised recipient.

Confidential projects. Disposal forecasts, valuations, letters of intent: these documents rarely leave the firm, and rightly so. If they must go out, prefer an encrypted transmission, and keep fax for the acknowledgement of receipt.

Setting up your workstation: the bare essentials

A clean document workflow takes very little.

• Scanning. A compact sheet-fed scanner is enough for a very small business; beyond 200 pages a month, investing in a networked model pays for itself in a single closing season.
• Physical separation. A multi-tier sorting tray, one per category (to fax / faxed / to upload), prevents double sending and oversights.
• Destruction. Draft return packages, redacted statements and failed pages do not go into the office bin. A P-4 level cross-cut shredder is the reasonable standard for accounting documents.
• Physical archiving. Ten years is a long time. Reinforced cardboard archive boxes, labelled by financial year, cost less than a day spent searching during an audit.
• Training yourself. A practical business accounting guide updated to the current chart of accounts saves plenty of back-and-forth with the firm over elementary questions.

Frequently asked questions

Does a faxed document have the same value as an accounting original?

No. Fax transmits an image; it does not create an original and does not exempt you from keeping the original document for ten years (article L.123-22 of the French Commercial Code). For a digital copy to replace a paper original, the reliable digitisation conditions of the order of 22 March 2017 must be met.

Can I file my annual accounts by fax with the court registry?

No. Accounts are filed electronically via the one-stop business formalities portal, or on paper with the registry. Fax is used only for ancillary exchanges: a missing document, a response to an observation, a power of attorney.

Can my accountant refuse a document received by fax?

Yes, if the engagement letter designates another channel as the official route for transmission, or if the image quality does not allow reliable transcription. Always duplicate the transmission on the channel set out in the contract.

How long should I keep transmission reports?

Align them with the document concerned. For an accounting document, ten years. For an exchange linked to a dispute, until the applicable limitation period expires, generally five years in commercial matters.

What should I do if I faxed a return package to the wrong number?

Act immediately: identify the holder of the number, request destruction of the document in writing, document the steps taken. If employees' personal data are involved, notification to the CNIL may be required within 72 hours. See our FAQ and the detailed procedure in our article dedicated to misdirected transmissions.

Is fax cheaper than a registered letter for a formal notice to a supplier?

Considerably, but it does not replace one when a limitation deadline is at stake. The tried-and-tested practice: fax on the day for the date, registered letter the next day for enforceability.

In summary

• Fax never creates an accounting original: it transmits an image, and the ten-year retention obligation remains fully in force.
• It is useful in three specific windows: an isolated document to a third party without a portal, a deadline expiring the same day, and a banking or financing file.
• It duplicates the channel set out in the engagement letter, it does not replace it.
• Always archive the triptych: exact copy of the pages, transmission report, record in the tool.
• Named cover sheet, number checked twice, redacted documents: three habits that prevent confidentiality incidents.
• For the most sensitive items — payroll, valuations, bank details — favour an encrypted channel and keep fax for the acknowledgement of receipt.

To prepare transmissions to correspondents outside France, check the list of available countries and the applicable dialling codes beforehand.