How to file a patent in France: the complete step-by-step guide to protecting your invention

You have designed a product, a process, or a technical improvement, and you worry that a competitor will seize it before you have secured your rights. Filing a patent with the INPI (the French intellectual property office) is the only mechanism that grants an exclusive right to exploit an invention, enforceable against third parties on French territory. Without this title, your innovation remains legally vulnerable, no matter how much time you have invested in developing it.

This guide covers the patentability requirements set out in the French Intellectual Property Code, the preliminary steps to anticipate, the procedure before the INPI, the applicable fees, and the obligations that follow grant. Romain Waiss-Moreau assists at every stage, from the prior art assessment through to infringement litigation.

Why file a patent to protect your invention?

A patent is an industrial property title that grants its holder an exclusive right of exploitation for a maximum of twenty years from the filing date. During that period, you alone decide who manufactures, markets, imports, or uses the invention. Any exploitation by a third party without your authorization constitutes infringement, engaging their civil liability, and where applicable their criminal liability, before the competent tribunal judiciaire (the French civil court).

“Any invention may be the subject of an industrial property title granted by the director of the Institut national de la propriété industrielle, which confers on its holder or successors in title an exclusive right of exploitation.” (article L. 611-1 of the French Intellectual Property Code)

The benefits go beyond defending against copying. A patent is an intangible asset that can be recorded on the balance sheet and weighs in the company's valuation during a fundraising round, a sale, or an acquisition. It also opens the door to licensing agreements paid through royalties, to coexistence agreements, or to partial assignments by product class.

Conversely, failing to file exposes you to several concrete legal risks:

• free copying by a competitor who files first and acquires enforceable prior rights;

• public disclosure destroying novelty, a requirement for patentability;

• inability to assign or license a right that does not exist as a title;

• an inadmissible infringement action, for lack of a title to assert.

What are the requirements for a valid patent?

The French Intellectual Property Code makes the grant of a patent subject to three cumulative requirements: the invention must be new, involve an inventive step, and be capable of industrial application. Failing a single criterion leads to rejection of the application by the Institut national de la propriété industrielle or, after grant, to the title being invalidated by the tribunal judiciaire.

Certain creations are excluded by nature from the scope of patentability, regardless of their merits: discoveries, scientific theories and mathematical methods, computer programs as such, business methods, presentations of information, as well as methods of surgical or therapeutic treatment. Software qualifies for a patent only if it produces a further technical effect, for example by controlling an industrial device. Romain Waiss-Moreau performs a preliminary qualification of the invention to rule out these exclusion zones before any filing.

What preliminary steps before filing a patent with the INPI?

Before any filing, a preparatory phase determines the strength of the future title. The first step is to conduct a thorough prior art search to verify that the invention has not already been disclosed. This search covers the INPI patent database, Espacenet for European and worldwide titles, and non-patent scientific literature. A single enforceable piece of prior art, however obscure, is enough to destroy novelty and therefore the title.

Drafting the claims comes next, under strict confidentiality. They define the exact scope of the monopoly and determine the reach of the protection. Wording that is too broad exposes the application to rejection for lack of novelty or inventive step; wording that is too narrow leaves third parties room to design around the protection. In parallel, the applicant decides on the geographic scope: the French national route, a European patent through the EPO, or an international PCT application allowing the choice of countries to be deferred for up to thirty months.

To establish a certain date before filing, the enveloppe Soleau (a sealed evidentiary filing with the INPI) or an evidentiary deposit with a public officer remains useful. Romain Waiss-Moreau recommends, at this stage, involving a French patent attorney (conseil en propriété industrielle) or a lawyer who practices patent law: under article L. 612-1 of the French Intellectual Property Code, the quality of the initial drafting determines the very admissibility of the application.

How to file a patent with the INPI: the procedure step by step

Filing is done exclusively online, through the INPI portal. The file includes the request form, the technical description, the claims, any drawings, and the abstract. Once the application is registered, the Institute checks its formal admissibility, then forwards the file to the national defense authorities for disclosure clearance. Next comes the preliminary search report, accompanied by a written opinion on patentability, to which the applicant responds with observations or new claims; failure to respond is a ground for rejection under article L. 612-12 of the French Intellectual Property Code.

Throughout the procedure, the applicant retains the right to amend the claims within the limits of the initial content of the description. Romain Waiss-Moreau builds each response to the examiner with you, a decisive step for the final scope of the granted title.

How much does filing a patent cost and what timelines should you expect?

The cost of a French patent breaks down into two separate blocks: the official fees paid to the INPI, whose amounts follow the current INPI fee schedule, and the fees of the patent attorney or lawyer who drafts the application. The main official fees are the filing fee (around 26 euros), the search report fee (around 520 euros), and the grant fee (around 90 euros), plus annuities, which increase progressively over twenty years. Individuals, SMEs with fewer than 1,000 employees, and nonprofit organizations benefit from a 50% reduction on most of these fees, upon supporting documentation filed with the application.

As for timelines, grant occurs on average within two to three years of filing, with the preliminary search report issued around the ninth month and publication in the BOPI at the eighteenth month. Romain Waiss-Moreau sets out the full budget envelope and the expected procedural timeline from the initial quote.

What obligations after filing your patent?

The grant of the title opens an active phase of maintenance and defense. Each year, the holder must pay an annuity to the INPI, on pain of forfeiture of the patent. The fee scale increases over the twenty years of protection: modest in the early years, it reaches several hundred euros toward the end of the period, which requires regularly weighing the economic value of keeping the title in force.

Actually working the invention underpins the strength of the monopoly. Absent serious exploitation within three years of grant (or four years of filing), a third party may seek a compulsory license before the tribunal judiciaire. Monitoring infringements of the monopoly defined by article L. 613-3 of the French Intellectual Property Code also falls to the holder: unauthorized manufacture, offering, importation, or use of the patented product or process all constitute acts of infringement that must be stopped.

Two reflexes are worth putting in place from the moment of grant:

• International extension: the priority right under the Paris Convention opens a twelve-month window from the French filing to extend protection abroad (the European route through the EPO or the international route through the PCT) while keeping the initial priority date.

• Product marking: indicating the patent number on marketed products makes it easier to establish the infringer's bad faith and strengthens the calculation of damages.

Securing your patent filing with expert guidance

The grant procedure combines three mutually reinforcing constraints: strict patentability requirements (absolute novelty, inventive step, industrial application), demanding technical drafting where the slightest imprecision in the claims narrows the scope of the monopoly, and financial stakes spread over twenty years between maintenance fees, international extensions, and potential infringement litigation.

In this field, two roles complement each other. The French patent attorney (conseil en propriété industrielle) brings expertise in claim drafting, thorough prior art searching, and territorial extension strategy. The lawyer who practices patent law handles contractual protection (assignments, licenses, confidentiality agreements), employee inventions within the meaning of the French Intellectual Property Code, and litigation defense in the event of a proven infringement. The two roles are distinct but often work together on the same matter.

Romain Waiss-Moreau handles the following legal aspects:

• Patentability audit and the choice between a patent, trade secrets, and defensive publication.

• Drafting and negotiating patent assignment, license, and co-ownership agreements.

• Handling employee inventions and the additional compensation they entail.

• Litigation strategy, infringement seizure (saisie-contrefaçon), and infringement actions before the tribunal judiciaire.

Contact Romain Waiss-Moreau to structure your patent filing and secure the title throughout its term of protection.

Frequently asked questions

Can I file a patent myself without going through a professional?

Nothing prohibits it for a French applicant residing in France. The INPI accepts direct filings through its online portal. The difficulty is not administrative but a matter of drafting: the scope of the monopoly depends entirely on the quality of the claims. Wording that is too broad weakens the title against prior art, while wording that is too narrow lets competitors design around the protection. For a patent with real economic stakes, involving a patent attorney for the drafting and a lawyer for the contractual aspects remains the norm.

What happens if I disclose my invention before filing?

Prior disclosure destroys novelty, a patentability requirement under the French Intellectual Property Code. A scientific publication, a trade show presentation, or a business discussion without a confidentiality agreement is enough to jeopardize the grant. French law provides no general grace period. The practical rule is simple: file before any communication, or frame every preliminary exchange with a written confidentiality agreement that precisely identifies the protected subject matter and the duration of the commitment.

Does an invention I made during my employment belong to me?

The answer depends on the regime set by the French Intellectual Property Code. Inventions made under an inventive mission, created in the performance of a contract that includes inventive duties, belong to the employer, with the employee receiving additional compensation. Inventions made outside that mission but attributable to it may be claimed by the employer in exchange for a fair price. All others remain the employee's property. The exact legal qualification determines who owns the filing and the amount due; it should be settled before filing, not after.

What should I do if I discover a competitor exploiting my patented invention?

Any manufacture, offering, placing on the market, or importation of the patented product without the holder's consent constitutes infringement engaging the infringer's civil liability under the French Intellectual Property Code. The first step is to build the evidence: a bailiff's report, a test purchase, then an infringement seizure (saisie-contrefaçon) ordered by the tribunal judiciaire. A formal notice may precede the action, but it alerts the opponent. The choice between negotiation and litigation is made after assessing the strength of the title and the scope of the infringement.