Filing a patent in France: procedure, cost and strategy in 2026

Filing a patent in France: procedure, cost and strategy for startups (2026 Guide)

In 2026, patent applications in France are filed exclusively online with INPI. For a startup, managing the priority date, budget and international extension strategy determines both protection and fundraising capacity. Here is a practical guide, aligned with INPI practices and tailored to founders.

1) Patentability prerequisites to check first

The Code de la propriété intellectuelle requires the invention to be new, involve an inventive step and be capable of industrial application (CPI, art. L.611-10 et seq.). Any public disclosure before filing destroys novelty, subject to very limited exceptions. In other words, a public pitch, trade-show demo, open GitHub repository, blog post or preprint = major risk.

• Software: not patentable “as such”, but a software solution associated with a technical effect may be. See our dedicated analysis of software patents in France and Europe.
• Fatal mistakes: publishing a white paper, building a community on Product Hunt or uploading an explanatory video before filing. Use NDAs and control communications.

For these fundamentals, INPI summarizes the key filing stages and criteria here, and the government explains the online procedure here.

2) INPI procedure: the complete process (2026)

Step 1 — Thorough prior-art search

This is not optional. Examine patent literature (published patents, pending applications) and scientific/technical literature. Start with INPI public databases and organize keyword/IPC searches. INPI describes the approach and tools in its filing stages. Practical guides illustrate good practice for searches and framing claims (Facture.net ; Déposer-brevet.com).

Step 2 — Drafting the application

• Description that is complete and reproducible by a person skilled in the art.
• Claims (the legal core of the monopoly), drawings if useful, abstract.

“pro-business” drafting anticipates variants, industrialization and design-around options. For startups, we favor a robust main claim plus adaptable dependent claims for international use. Useful methodological reminders in these practical summaries (Ipside ; Dhenne Avocats ; We Are Bold).

Step 3 — Online filing and priority date

File through the INPI online procedure, which establishes the filing date (your priority anchor). Pay fees at filing to avoid irregularities.

Step 4 — Search report and observations

You receive a search report with a written opinion. Typical response period: 3 months (extensions possible). This is the key moment to amend the claims and position the invention in a clear area of patentability. INPI describes the milestones here, also covered by practitioners (Ipside).

Step 5 — Publication at 18 months

Publication of the application in the BOPI 18 months from priority: a deterrent to competitors, but also disclosure of your technology. Plan announcements and additional filings accordingly.

Step 6 — Grant and opposition

After substantive examination and payment of the grant fee, the patent is published as granted. An opposition by third parties is possible within 9 months of grant (mechanism detailed by INPI, see stages). Do not forget annual renewal fees to keep the patent in force.

Indicative timeline (standard application)

• Filing day 0 → priority secured
• Search report: 6–12 months
• Publication: 18 months
• Grant: 24–30 months on average

3) How much does a French patent cost in 2026?

Indicatively (a “small entity” startup), according to INPI 2026 fee schedules and official guides:

• Filing fee: ~36 €
• Search fee: ~520 €
• Grant fee: ~42 €
• Annual renewal fees: increasing each year (budget over 20 years)

INPI summarizes milestones and payments here, and the government here. Useful private-sector summaries showing the sequence of costs: Ipside, Déposer-brevet.com, Dhenne Avocats, We Are Bold.

Drafting budget (professional fees): varies by complexity/sector (often several thousand euros). Anticipate this item in your startup legal budget.

4) Startup protection strategy: 0–24 months

Before filing: no disclosure

• Avoid any public publication. Govern exchanges through non-disclosure agreements (NDAs).
• Check that rights to inventions actually belong to the company (founders, freelancers, interns). If necessary, formalize an assignment of founders’ rights to the company.
• Protect brand identity alongside the technology: protecting the name and registering the trademark prevent go-to-market obstacles.

First filing and “12-month priority”

Proven startup practice: make a first French filing promptly (description + sufficiently broad initial claims), to establish priority, then improve and extend within 12 months (EPO/Unitary or PCT). Beforehand, you can date certain iterations through an Enveloppe Soleau (evidence of prior creation, not a substitute for a patent).

Extend intelligently: Europe and worldwide

• European route (EPO), then unitary effect: a single grant, with possible unitary effect covering many Member States together.
• PCT: defer national costs until approximately 30/31 months, useful when the market/technology is uncertain. Secure your cash runway before national phases.

External step-by-step guides help visualize these branches (Facture.net ; We Are Bold ; Ipside).

Patent vs trade secret

If the competitive advantage lies in a configuration that is difficult to reverse-engineer (e.g. a trigger threshold in edge computing), a trade secret may be preferable to a patent. Conversely, if the solution will be apparent in the finished product, a patent is needed.

Special case: software-first

If your innovation is software-based, assess patentability through the technical effect and secure copyright in the source code alongside it (source-code protection). Our “software patent” article details the criteria and concrete cases.

5) Implementation checklist

• Day -30 to day 0: prior-art search, claim scoping, NDAs with partners, internal R&D/product approval.
• Day 0: online INPI filing, fee payment, document checks.
• +3–6 months: receipt of search report, reasoned response, possible amendments.
• +12 months: extension decision (EPO/Unitary, PCT) based on market traction and budget.
• +18 months: BOPI publication, align “patent pending” communications.

6) Common startup mistakes (and how to avoid them)

• Disclosing before filing: novelty is destroyed. Run demos under NDA and limit public content to business benefits, without exploitable technical disclosure.
• Overly narrow drafting: claims covering only a prototype. Anticipate industrial variants and competitors’ design-around routes.
• Forgetting the chain of rights: no assignment from founders/developers. Formalize IP assignment to the company and invention clauses in contracts.
• Waiting too long to go international: after 12 months, priority is lost. Decide early on the EPO/Unitary or PCT route.

Anecdote (experience) — One of our clients, a deeptech sensor startup, was preparing to present a proof-of-concept at a trade show. We spotted that the demo explained a novel calibration algorithm. Within 72 hours, we finalized a French first filing (main claim + 8 dependent claims) and secured exchanges with partners under NDA. Ten months later, the company chose the PCT route, then unitary effect after EP grant — this optimized timing enabled it to announce “patent pending” at Series A while spreading costs.

Quick FAQ

How long does it take to obtain a French patent?
Generally 24 to 30 months from filing to grant, with publication at 18 months.

How much does it cost?
INPI fees: approximately €600 (filing, search, grant) + annual renewal fees. Budget for drafting/response fees.

Can I discuss it with investors before filing?
Only under a strict NDA. Any public disclosure can destroy novelty.

Software: patentable or not?
Not “as such”; patentable if it makes a technical contribution. Also protect copyright in the code.

Useful references: online procedure (Service‑Public) ; INPI stages; practitioner guides: Ipside, Déposer-brevet.com, Facture.net, Dhenne Avocats, We Are Bold.