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EPO guide

The European Patent Convention, annotated

By , Co-founder and CEO, PatentAssist.ai
Updated

The European Patent Convention runs to 178 Articles plus its Implementing Regulations, and the full text is on epo.org. What is harder to find is a plain account of the 25 provisions that come up again and again when you draft and prosecute a European application. These notes quote the key words of each one, explain what it means in practice, and set out the deadlines, fees, Enlarged Board decisions and objections that go with it.

Quick answer

  • What it is: the treaty that created the European Patent Office. One application, one search and one examination lead to a European patent for up to 40 member states.
  • Two layers: Articles set the law; Rules set procedure and time limits. Articles prevail in a conflict (Article 164(2)).
  • How it is applied: the EPO's Guidelines for Examination (April 2026) and the decisions of the Boards of Appeal, above all the Enlarged Board's G decisions.
  • Recent changes: G 1/24 (claims are always read with the description), G 1/23 (products on the market are prior art even if they cannot be reproduced) and G 1/25 (when the description must be adapted to amended claims).

What the EPC is

The Convention on the Grant of European Patents was signed in Munich on 5 October 1973 and revised by the Act of 29 November 2000, which produced the version in force today, usually called EPC 2000. It set up the European Patent Organisation, which now has 40 member states, the most recent being the Republic of Moldova from 1 June 2026. It is not an EU instrument: the United Kingdom, Switzerland, Norway and Türkiye are members too.

The EPC centralises the grant procedure, not the patent itself. After grant, a European patent becomes a bundle of national patents in the states where it is validated, or a Unitary Patent for the participating EU states. Its extent of protection is still governed by the EPC (Article 69), and it can be centrally opposed at the EPO for nine months after grant.

For the end-to-end process, costs and fees, see our guide to the European patent application. The pages below go one level deeper, provision by provision.

How Articles, Rules, Guidelines and case law fit together

Answering an EPO question usually means reading four sources in order. Take a typical one: may I add a feature from the examples to claim 1? The Article (123(2)) gives the principle, the Rule (137) says when and how amendments are filed, the Guidelines (H-V, 3.2.1) describe how examiners treat intermediate generalisations, and the case law (G 2/10 and many T decisions) sets the test they apply.

Source What it covers Legal weight
Articles The Convention itself: what is patentable, what an application must contain, the main procedural steps and the effects of a European patent. Binding. Prevail over the Rules in a conflict (Article 164(2)).
Implementing Regulations (Rules) The detail behind the Articles: time limits, formal requirements, communications and how fees are triggered. Amended by the Administrative Council more often than the Articles. Binding, and an integral part of the Convention (Article 164(1)).
Rules relating to Fees The amounts of the official fees and the further processing fee. The current schedule applies from 1 April 2026. Binding.
Guidelines for Examination The EPO's instructions to its examiners on how to apply the Articles and Rules, updated each year (current edition April 2026). Not binding law, but examiners follow them, so they predict what will happen in your file.
Case law of the Boards of Appeal Decisions of the Technical and Legal Boards (T and J decisions) and of the Enlarged Board (G decisions), which settles points of law. G decisions are followed throughout the EPO; T and J decisions are persuasive.

Two cautions. First, numbering changed with EPC 2000, so decisions from before December 2007 often cite old Rule numbers: Rule 86(4) in T 708/00 is today's Rule 137(5). Second, the Rules change more often than people expect; Rule 56a on erroneously filed documents only arrived on 1 November 2022. Always check the current text on epo.org.

The annotated provisions

Each page quotes the provision verbatim, links to the official text, and adds a plain-English explanation, the time limits and fees, the leading decisions, the objections examiners raise and practical tips.

Patentability

What can be patented at all, and what counts against novelty.

Provision What it covers
Article 52 Patentable inventions The four conditions for a patent and the list of non-inventions, including computer programs “as such”.
Article 53 Exceptions to patentability Ordre public, plant and animal varieties, and methods of surgery, therapy and diagnosis.
Article 54 Novelty Novelty: the state of the art, earlier unpublished European applications and medical-use claims.
Article 57 Industrial application Industrial application: usually easy, but a real hurdle for sequences and speculative research tools.
Article 56 Inventive step Covered in our guide: The problem-solution approach to inventive step at the EPO . Official text

Application requirements

What the application must contain and how it must be drafted, including priority and divisionals.

Provision What it covers
Article 76 European divisional applications What a divisional may contain, the filing date it inherits and the rules for chains of divisionals.
Article 82 Unity of invention One invention per application, or a group linked by a single general inventive concept.
Article 83 Disclosure of the invention Sufficiency: the application must let the skilled person carry out the invention across the claim's scope.
Article 84 Claims Claims must be clear, concise and supported by the description; G 1/25 on adapting the description.
Articles 87 to 89 Priority right, claiming priority and effect of priority right The 12-month priority right, the “same invention” test, multiple and partial priorities, and its effect.
Rule 36 European divisional applications When a divisional can be filed (any pending parent), its language and fees, including the generation fee.
Rule 42 Content of the description The required content and order of the description, from technical field to industrial application.
Rule 43 Form and content of claims Two-part claims, one independent claim per category, dependent claims and reference signs.
Rules 56 and 56a Missing parts and erroneously filed documents Filing missing pages or drawings, or correcting wrongly filed documents, and when the filing date moves.

Search and examination procedure

The communications that drive the file from search to grant, and the deadlines that come with them.

Provision What it covers
Article 153 The European Patent Office as designated Office or elected Office How a PCT application becomes a Euro-PCT application, and the 31-month entry into the European phase.
Rule 62a Applications containing a plurality of independent claims The invitation to pick which independent claims are searched when Rule 43(2) is not met.
Rule 63 Incomplete search Partial search or no search where the claims are too unclear or non-technical to search meaningfully.
Rule 64 European search report where the invention lacks unity Partial search on the first invention and the invitation to pay further search fees for the others.
Rule 70a Response to the extended European search report The mandatory reply to a negative search opinion, due with the request for examination.
Rule 71(3) Examination procedure (intention to grant) The intention-to-grant communication: approve the text, pay the grant fee and file claim translations in 4 months.
Rule 112 Noting of loss of rights The EPO's notice that a right has been lost, and the routes back: a decision, further processing or re-establishment.
Rule 137 Amendment of the European patent application When amendments are allowed, how their basis must be shown, and the bar on unsearched subject matter.
Rules 161 and 162 Amendment of the application; claims incurring fees The 6-month period after Euro-PCT entry to reply to the international opinion, amend and pay claims fees.
Rule 164 Unity of invention and further searches Further search fees for Euro-PCT inventions the EPO has not searched, in the supplementary search or examination.

Scope of protection and post-grant

How the claims are read, and the limits on amending an application or patent.

Provision What it covers
Article 69 Extent of protection The claims define the protection; the description and drawings are always used to interpret them (G 1/24).
Article 123 Amendments Amendments: no added matter (123(2)) and, after grant, no extension of protection (123(3)).
Articles 99 to 101 Opposition Covered in our guide: European patent opposition at the EPO . Official text

The time limits that cost applicants most

Most EPC deadlines are generous but unforgiving. Several of the short ones cannot be rescued by further processing, so they belong at the top of any docket.

Step Time limit Notes
File in Europe claiming priority 12 months from the first filing Articles 87 to 89 EPC
Enter the European phase from a PCT application 31 months from the earliest priority date Article 153 EPC
Missing or wrongly filed parts 2 months from filing or from the EPO's invitation Rules 56 and 56a EPC
Reply to a Rule 62a, Rule 63, Rule 64 or Rule 164 invitation 2 months, with no further processing Rule 64 EPC
Reply to a negative search opinion 6 months from the mention of the search report Rule 70a EPC
Reply and amend after Euro-PCT entry 6 months from the Rules 161 and 162 communication Rules 161 and 162 EPC
Approve the text: grant fee and claim translations 4 months from the Rule 71(3) communication, not extendable Rule 71(3) EPC
File a divisional While the parent is pending; before the mention of grant Rule 36 EPC
Further processing after a missed time limit 2 months from the loss-of-rights communication Rule 112 EPC

Fees quoted on these pages are from the Rules relating to Fees in force from 1 April 2026, for example €1,135 for the fee for grant, €1,595 for each further search fee and €315 for further processing of most acts other than fee payments.

Three recent decisions to know

G 1/24 (18 June 2025). The description and drawings must always be consulted when interpreting claims for patentability, not only when a claim is unclear. Definitions in the description now matter at the EPO as much as in court. See Article 69 EPC.

G 1/23 (2 July 2025). A product put on the market is prior art even if its composition could not be analysed and reproduced. See Article 54 EPC.

G 1/25 (3 September 2026). Where amended claims leave the description inconsistent and that inconsistency breaches Articles 52 to 57, 76(1), 83, 84 or 123, the description must be adapted. The April 2026 Guidelines predate it. See Article 84 EPC.

Draft to the EPC from the first version

Most of the problems on these pages start in the first draft: claims that breach Rule 43(2), descriptions with no stated technical problem, and too few fallback positions to amend into under Article 123(2). PatentAssist.ai drafts claims, the description and the abstract in EPO format from your invention disclosure, and its prior-art search covers EPO, USPTO and Indian records, so you can check novelty before you file. It does not draft replies to EPO communications.

Try drafting free for 7 days Search EPO prior art

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European Patent Convention: frequently asked questions

What is the European Patent Convention?

The European Patent Convention (EPC) is the treaty, signed in Munich on 5 October 1973 and revised in 2000, that created the European Patent Organisation and the European Patent Office. It sets one procedure for filing, searching, examining and granting European patents, which then take effect in the member states chosen by the applicant. The Organisation has 40 member states, including all EU states and others such as the United Kingdom, Switzerland, Norway and Türkiye.

What is the difference between EPC Articles and Rules?

The Articles are the Convention itself and set the principles, such as novelty in Article 54 or amendments in Article 123. The Rules, formally the Implementing Regulations, set the procedure and time limits, such as Rule 71(3) for the intention to grant. The Rules are part of the Convention, but if they conflict with an Article, the Article prevails under Article 164(2).

Are the EPO Guidelines legally binding?

No. The Guidelines for Examination are the EPO's instructions to its examiners and are revised every year. They are not law, and the Boards of Appeal can depart from them, but examiners follow them closely, so they are the best guide to how your application will be handled.

What does EPC 2000 mean?

EPC 2000 is the version of the Convention revised by the Act of 29 November 2000. It is the version in force today, and the EPO's current consolidated text is the 17th edition, published as “EPC 2020”, with later amendments to the Rules shown on epo.org. Older decisions cite the EPC 1973 numbering, so a rule number in an old decision may not match today's Rule.

Is there a grace period for disclosures under the EPC?

Not a general one. Article 55 disregards a disclosure made no earlier than six months before filing only if it was an evident abuse against the applicant or a display at an officially recognised international exhibition. Any other public disclosure before the filing or priority date counts as prior art under Article 54(2).

What happens if I miss an EPO deadline?

Most missed time limits before grant can be remedied by further processing under Article 121 and Rule 135: pay the fee and complete the act within two months of the EPO's communication, with no reason needed. Some periods are excluded, including the priority year and the replies under Rules 62a, 63, 64 and 164. For those, re-establishment of rights under Article 122 may be available if all due care was taken.

Sources: European Patent Convention, the Articles and Rules linked on each page and Article 164; Guidelines for Examination in the EPO, April 2026; Rules relating to Fees from 1 April 2026; EPO member states; decisions of the Boards of Appeal. This guide is general information, not legal advice.

EPC excerpts are quoted from the European Patent Convention, 17th edition, as amended and published by the European Patent Office. Practice notes follow the Guidelines for Examination in the EPO (April 2026) and the Boards of Appeal decisions cited. Fees are those in force from 1 April 2026. This is general information, not legal advice: check the official text and confirm deadlines with a European patent attorney.