Fax and the town hall: planning permission, civil registry, deadlines

Short answer: when dealing with a town hall, a fax will not file a building permit application and will not issue a birth certificate — but it does save a date. Three situations still justify it: an additional document requested by the case officer before the end of the review period, a comment to be entered in the register of a public inquiry closing within hours, and an informal appeal or a request for withdrawal that needs a timestamp when the digital portal is unavailable. Since 2022, French municipalities have had to offer an online service for planning permissions (the guichet numérique des autorisations d'urbanisme, or GNAU): that is the channel to use first. The fax comes as a backup, with a transmission report showing the date, time, number dialled and page count. On the other hand, for anything involving named civil registry records, fax should be handled with care: it carries personal data to a shared machine.

What the town hall accepts, and what it refuses

A municipality is not a single interlocutor. Behind the same switchboard you will find a planning department, a civil registry office, a municipal police force, a social action centre (CCAS), an electoral roll service and sometimes a water utility. Each has its own admissibility rules, and those rules depend not on the channel but on the legislation governing the procedure.

Three regimes coexist.

Procedures with a mandated channel. Filing an application for a building permit, a development permit or a prior declaration must follow the forms set out in the French planning code: submission at the town hall against a receipt, registered post with acknowledgement of receipt, or the online service where the municipality provides one. The code governing relations between the public and the administration (CRPA) also establishes the right to contact the administration electronically. A fax is not on that list: it does not bring a case file into existence.

Procedures with no prescribed form. A request for information, a complaint, sending a missing document for a file already registered, a comment submitted as part of a consultation: no legislation imposes a medium. Here, fax is perfectly acceptable, and its transmission report carries the same evidential weight as an email acknowledgement — often better, because it is produced by third-party equipment rather than by your own software.

Procedures requiring verified identity. A full copy of a birth certificate, a family record book, or registration on the electoral roll all require the officer to be sure who is asking for what. A fax carries no authentication. The request may well be received, but it will not be granted without legible proof of identity — and an identity scan coming out on a shared paper tray is exactly what you want to avoid.

Planning: fax's real playing field

It is in planning matters that the question of dates becomes critical, because administrative silence produces legal effects there. Once the review period has elapsed — one month for a prior declaration, two months for a building permit concerning a single-family house, three months in other common cases — a tacit decision comes into being. In other words: your permission exists because nobody replied.

The whole issue then becomes knowing when the period started, and above all proving that a request for additional documents was satisfied within the three-month period laid down by the planning code. A file that remains incomplete beyond that point is deemed withdrawn. Disputes very often arise right there: the applicant insists they sent the corrected site plan, and the case officer cannot find it.

In that specific situation, the effective sequence is as follows.

1. Submit the document on the digital portal of the municipality or the inter-municipal authority and keep the electronic registration receipt (AEE) and then the electronic acknowledgement of receipt (ARE) provided for by the CRPA.
2. If the portal is under maintenance, overloaded, or if the file exceeds the accepted size — which happens quickly with heavy plans — send the document by fax to the planning department, with a cover page restating the file reference number (the familiar DP or PC followed by the municipality's Insee code, the year and a sequential number).
3. Back it up with registered post the same day if the project's financial stakes warrant it.
4. Archive together the transmission report, the document sent and the departmental request that called for it.

This triple-channel logic is not administrative paranoia: it is the same approach applied to time-limited submissions with a public officer, set out in detail in our article on dated submissions in public procurement and with a notary. A deadline that is running can never be caught up.

The case of site notices and third-party appeals

Another little-known use: challenging a decision. A neighbour who spots a permit display board has two months to lodge an informal appeal with the mayor, and must notify their appeal to both the author of the decision and the holder of the permission within fifteen clear days, in accordance with Article R. 600-1 of the planning code. This notification is a condition for the admissibility of any subsequent court action.

The legislation refers to a registered letter. Fax is no substitute for it. But when a fifteen-day deadline falls due on a Saturday, having sent the notification by fax in addition to the registered letter posted the same day provides a second timestamped record. In the same spirit, photographing the display board at regular intervals, with the date, using a simple compact digital camera, amounts to far stronger evidence than the memory of a date.

Civil registry and personal data: the clear limit

The civil registry office handles named records, references to parentage and sometimes sensitive family situations. The CNIL regularly points out that fax remains a form of personal data processing like any other: it falls under the GDPR, with the same obligations of data minimisation and security.

Two practical rules follow.

The first: send only what is necessary by fax. A request for a certificate does not need your tax assessment notice. An acknowledgement of debt has no place in a marriage file.

The second: know where the page comes out. In a small municipality, the fax machine is often in the general secretariat, in a corridor people walk through. A birth certificate mentioning an adoption sitting for two hours on a shared paper tray is a data breach, even without any intent. When the subject matter is sensitive, prefer a traced and encrypted channel — we compare the two approaches in fax or secure messaging.

The same vigilance applies at the sending end. If you are a local authority officer, a fax machine connected to a multifunction printer locked with a PIN code, or a cross-cut document shredder within easy reach, says far more about a department's rigour than any charter pinned to the wall.

Decision table by procedure

That last row deserves a word. The right of access to administrative documents, organised by the CRPA and clarified by the opinions of the Commission for Access to Administrative Documents (CADA), requires a written request addressed to the administration. Silence maintained for one month counts as a refusal and opens the way to referring the matter to the CADA. Here again, everything rests on the start date: a timestamped fax fixes that starting point beyond dispute.

Public inquiry: the hour matters, not the day

Public inquiries — revision of a local planning scheme, a development project, a classified installation — close at a precise time stated in the opening order. Comments can generally be entered in the paper register, sent to the inquiry commissioner by post, or submitted on a digital register.

Many associations and local residents only find out about the closing date the day before. In that situation, sending the comment by fax to the town hall hosting the inquiry, with a copy to the inquiry commissioner if a number is published, makes it possible to obtain a record accurate to the hour. The transmission report shows the exact time transmission ended: that is precisely the information you will need if anyone claims your contribution was late.

Two practical tips for these last-minute transmissions. Number your pages in plain text ("1/7", "2/7"): a page lost in an unnumbered transmission is impossible to detect. And if your contribution includes photographic annexes, bear in mind that a fax will render them in halftoned black and white: it is better to attach high-contrast graphic documents and save the colour version for submission on the digital register. A portable document scanner and a pack of good-quality 80 gsm paper will spare you many illegible results at the other end.

Preparing the transmission properly: the cover page that makes the difference

A fax received at a town hall lands in a shared tray. Without clear identification, it can wander between departments for days. The cover page must let whoever picks it up work out in three seconds where to take it.

It should show, in this order:

• the recipient department in large characters ("Planning department — case review");
• the file reference number or the reference of the letter you are replying to;
• the subject in one line, mentioning the deadline if there is one ("Additional document — deadline expiring 14/10/2026");
• your full contact details, including a phone number;
• the total number of pages.

Get into the habit of keeping a paper copy of the complete transmission, cover page included, in a folder dedicated to the case. A lever arch archive box or reinforced punched pockets will do: the day a dispute opens, two or three years later, that folder is what your lawyer will ask for. The retention period to apply is the same as for your other acknowledgements, and we set it out in detail in how long to keep your fax receipts.

Frequently asked questions

Can a town hall refuse a fax?

It cannot refuse to receive one, but it can legitimately take the view that it does not constitute a valid submission for procedures with a mandated form. In practical terms, a faxed building permit application will not be processed. A faxed additional document for an existing file, on the other hand, will be added to that file in almost every case.

Is the transmission report enough to prove the town hall received the document?

It proves that transmission was completed and that a fax machine at the other end accepted the pages. It is prima facie evidence, freely assessed by the administrative court. It does not prove that the relevant officer read it. That is why backing it up with a channel that provides acknowledgement of receipt remains advisable whenever money is at stake.

How do I find the fax number for the right department?

First, on letters you have received from the municipality: the letterhead often shows the department's direct fax number. Otherwise, try the directory on the town hall's official website, or the service-public.fr portal, which aggregates contact details for French town halls. Avoid the generic switchboard number when a departmental number exists.

What if the municipality no longer has a fax machine?

This is increasingly common, with the shutdown of the switched telephone network. Check the number with a phone call before any time-limited transmission. If the line does not answer, switch immediately to the digital portal and electronic registered mail. Our feature on the end of the PSTN explains why some public numbers no longer answer.

Can you send a fax to a town hall from a computer?

Yes, using an online fax service: you upload a PDF, the service transmits it and sends you back a timestamped report. It is actually preferable, because the record is natively digital and easy to archive. The list of destinations covered is set out on our available countries page.

In summary

• A fax does not create a planning file: the digital portal, filing at the town hall or registered post remain the submission channels.
• It becomes valuable for saving a date: an additional document within the three-month period, a public inquiry comment before the closing time, a second record of an appeal notification.
• For civil registry matters, fax is not advisable: named data, output on a shared machine, no authentication of the requester.
• A complete cover page with department, file number, subject, deadline and page count determines whether the document reaches the right desk.
• Always archive the whole set: the document sent, the transmission report, and the town hall letter that requested it. Separately, these three items prove nothing.
• Before any time-limited transmission, check the line with a phone call: many municipal fax machines have been unplugged.