PCT National Phase Europe: 31-Month Timeline

Most US companies protect an invention at home first, then file a PCT application to keep foreign options open. By the 31-month deadline you must decide where to enter the national or regional phase. Choosing the European Patent Office is the usual answer for Europe — but the European regional phase is not a continuation of US prosecution. It is a fresh examination under the European Patent Convention, with its own timeline, fees and amendment windows.

The single date that governs everything is the earliest priority date, not the PCT filing date. The European regional phase must be entered within 31 months of the earliest priority date. Unlike the US national phase (30 months), Europe gives you one extra month — a difference that has caught out more than one US docket. The table above sets out the full month-by-month sequence for a typical case.

Entry itself is a fee-and-forms exercise, but the fee package is larger than most US applicants expect. At entry you pay the filing fee, the designation fee covering all EPC contracting states, the examination fee, and — where the application has more than fifteen claims or more than thirty-five pages — claims fees and page fees. Trimming the claim set before entry is often the cheapest single decision in the whole process. If the PCT was published in a language other than English, French or German, a translation is required at entry.

The most valuable window opens immediately after entry. The EPO issues a communication under Rule 161/162 EPC giving six months to amend the claims and settle claims fees. For applications where the EPO acted as International Searching Authority, this is also the moment to respond to the written opinion — and a response is mandatory, not optional. Using this window properly, with claims already aligned to European practice, usually removes a full round of examination later.

Two substantive rules cause most of the friction for US applicants. The first is Article 123(2) EPC on added matter: once the application is filed, you generally cannot introduce new technical information, even to distinguish prior art. Amendments that would pass at the USPTO are routinely refused at the EPO. The second is the problem-and-solution approach to inventive step: the EPO identifies the closest prior art, defines the objective technical problem solved by the difference, and asks whether the solution was obvious. Motivation-to-combine arguments familiar from US practice carry little weight. A fuller comparison is in the EPO vs USPTO practice guide.

The practical consequence is that the technical story must already be in the application as filed. New effects, advantages or combinations raised during prosecution risk being treated as added matter. The PCT specification — not later argument — is the foundation of your European claim scope, which is why the pre-entry review at months 28 to 30 matters more than anything you do after the first office action.

Missing the 31-month deadline is serious. Further processing is available in limited circumstances and re-establishment of rights requires showing all due care, both with additional fees and no guarantee of success. Diary the deadline from the priority date, and set an internal instruction date at least two months earlier so there is time for a claim review and a fee estimate.

If you have not yet filed the PCT, or you are choosing between the PCT route and a direct EPO filing within the twelve-month Paris year, see how to file a European patent from the US. For what happens after grant — national validation versus unitary effect — see European patent vs Unitary Patent.

The key takeaway is that the PCT is only a doorway. What happens inside the EPO depends on how well the application was prepared for European rules before the door opened, and on using the Rule 161 window instead of drifting into examination with US-style claims. If you want a fixed-fee regional-phase entry with a pre-entry claim review, see European patent prosecution services for US applicants.