How to File a Patent in France with INPI: A Practical Guide for Foreign Businesses

Filing a patent in France follows a familiar shape: you prepare an application, the office examines it, and a patent grants if it clears. What surprises foreign businesses is how much the French context has changed in recent years. France runs its national patent system through INPI (the Institut National de la Propriete Industrielle, the national industrial property office), it conducts proceedings in French, it generally expects foreign applicants to act through a local representative, and, since a wave of reforms commonly known as the PACTE law (around 2019 to 2020), it now substantively examines inventive step and offers a post-grant opposition that did not previously exist. This guide walks through the national route at INPI and then sets it against the European, Unitary and international alternatives, because the most important decision a foreign business makes here is which office to file at, not just how to file. It is general information, not legal advice.

The specification, the claims and the drawings

A French patent application generally consists of a request to grant, a description of the invention full enough to enable a skilled person to carry it out, one or more claims that define the protection you are seeking, an abstract, and any drawings needed to understand the invention. The claims do the legal work. They mark the boundary of what you can later enforce, so their drafting is where most of the value and most of the risk sits. A description that discloses a clever invention but claims it narrowly leaves the substance unprotected, while claims that overreach invite objections during examination or vulnerability later. This is craft work, and it is the main reason foreign applicants engage a qualified French patent attorney rather than filing raw.

France applies a strict approach to novelty. Any public disclosure before your filing date (or priority date, if you claim priority), whether you publish a paper, pitch to a manufacturer, exhibit at a trade fair or start selling, can destroy patentability. The defensive habit is simple: file before you disclose. If your invention is a technical one and you want a faster, lighter national right, France also offers a strengthened utility certificate; we cover that separately in our guide to the French utility certificate (the certificat d'utilite), and the PACTE reforms both lengthened its maximum term and made it convertible into a patent in some circumstances. Treat the precise scope and the conversion conditions as confirm-with-counsel rather than assuming them.

French-language filing and translation quality

INPI conducts proceedings in French, and the application documents are generally expected in French. It is sometimes possible to file in another language first and supply a French translation within a set period, but you should not rely on that as a default; confirm the current rule and the applicable deadline with INPI or a local representative before planning around it. Where translation is needed, treat its quality as a substantive issue, not an administrative one. A patent specification is a legal instrument, and a translation that subtly shifts the meaning of a claim term can narrow your protection or introduce ambiguity an examiner or an opponent will exploit. Use a translator experienced in patent work and have the French claims reviewed by your French attorney rather than accepting a generalist rendering.

The local-representative requirement for foreign applicants

If you have neither a residence nor a place of business in France (and, depending on the rules, within the EU or EEA), you will generally need to appoint a representative qualified to act before INPI, typically a French patent attorney (a conseil en propriete industrielle) or another authorised professional, to act for you and to receive correspondence. Treat representation as a structural requirement rather than an optional convenience, and build it into your timeline and budget from the outset; confirm the exact conditions, because they turn on where you are established. The same professional who handles your representation will usually draft or review the claims and manage the examination dialogue, so choosing well matters for the whole life of the application.

The PACTE reforms: substantive examination and post-grant opposition

Here is the change that most surprises applicants who last looked at the French system some years ago. Historically INPI granted patents after a fairly light review and did not refuse an application for lack of inventive step. Since the PACTE reforms, INPI substantively examines applications, including for inventive step, so a French national patent is now a more thoroughly examined right than it used to be. In practice that means examiners can raise objections on the merits and you respond by arguing, amending the claims, or both, within the deadlines the office sets.

The reforms also introduced a post-grant opposition procedure before INPI, an administrative route to challenge a granted French patent, distinct from court nullity proceedings, by which a third party can attack a patent within a set window after grant. If you are the patent holder this is a route by which your right can be challenged; if you are a competitor it is a route by which you can challenge someone else's. The opposition window, the grounds and the procedure are version-specific, so confirm the current position with INPI or local counsel rather than assuming any single timeframe.

The provisional application option

The PACTE package also added a provisional patent application, giving applicants a lighter, lower-cost way to secure an early filing date and then complete the application within a set period. The attraction is the same as an early filing anywhere: it can fix your priority date while you continue to develop the invention or assess its commercial promise. The trap is the same too. A provisional filing that is not completed and converted within the applicable period can be lost, and an under-detailed provisional may not properly support the claims you eventually want, so do not treat it as a way to skip careful drafting. The completion period and the exact mechanics are version-specific; confirm them with INPI or local counsel and diarise the deadline carefully.

Publication, examination and grant

French applications are generally published once a set period has elapsed after filing, which publishes the technical disclosure and starts certain provisional rights running. Examination then proceeds against the prior art for novelty, inventive step and the other patentability requirements, with one or more official communications raising objections or asking for clarification; you respond within the deadlines the office sets. These rounds are where the scope of your eventual patent is negotiated, and missing a response deadline can cost you the application, so this is the stage at which experienced local representation earns its keep. If the application clears examination, INPI grants the patent and publishes the grant.

Keeping the patent in force

Grant is not the end of the cost. Renewal (annuity) fees are not tied to grant; in France they run from the filing-date anniversary and can fall due even while the application is still pending. The precise schedule, when payment first falls due, and any grace periods are version-specific. Missing one can cause the patent or application to lapse, after which the protection is gone. Official fees apply; confirm the current schedule and amounts with INPI (or the EPO for a European or Unitary patent) or local counsel. Diarise renewals well ahead of each due date rather than relying on a single reminder. For the wider French patent picture, see the patents in France hub.

The European, Unitary and international routes

The national INPI filing is only one way to reach protection in France, and for many foreign businesses it is not the obvious one. Two regional and international layers sit alongside it, and conflating them with INPI is a common and expensive error.

The first is the European patent granted by the European Patent Office (EPO) under the European Patent Convention. The EPO is not an EU institution and is separate from INPI; it examines and grants a European patent centrally, which the holder then brings into effect (validates) in the individual member states they want, including France. On top of that, the Unitary Patent allows a granted European patent to take unitary effect across the participating EU member states in one step, with central renewal and central litigation through the Unified Patent Court, rather than a bundle of national rights. The territory covered is fixed at the date the unitary effect is registered and extends only to the EU member states then participating, not to all EPC states. Keep the institutions distinct: INPI is the French national office, the EPO grants European and Unitary patents, and the EUIPO (which administers EU trade marks and registered EU designs) has no role in patents at all. Whether the national INPI route or a European route serves you better depends on how many countries you are targeting: a single French market often points to a national filing, while a multi-country European footprint often points to the EPO.

The second layer is the Patent Cooperation Treaty. A single international application under the PCT secures an international filing date (and the benefit of any priority claim) recognised across the member states, and buys time, through an international phase, before you commit to and pay for protection in specific regions. You then enter the national or regional phase, and for France that typically means entering the European phase before the EPO rather than a separate French national phase, so check which phase applies to you. The national or regional-phase deadlines under the PCT are strict and forfeiting them is permanent, so confirm the applicable deadline before relying on it. For the wider mechanics, see our overview of the PCT route. Whichever route you choose, where your home country is a Paris Convention or WTO member you can claim priority from an earlier foreign application if you file within the priority period, which lets a first filing in your home country set the effective date for the French or European filing that follows; the length of that period is set by the rules, so confirm it rather than assuming.

A note before you file

IPEnvoy is not a law firm and does not provide legal advice; this is general information. The French system rewards early filing, careful claim drafting, attentive deadline management and a deliberate choice between the national, European, Unitary and international routes, and, since the PACTE reforms, a French national patent now carries the weight of full substantive examination and an opposition risk it did not before. Before you file, confirm the current position with INPI's official website and a qualified local IP professional, who can pressure-test your route choice, your disclosure timing and the French wording of your claims against the facts of your invention.