PCT application: Amendments to the claims

PCT: Änderung der Patentansprüche

The PCT application is a quick and easy way to file a patent application for an invention at only one office with effect for all countries or regions participating in the PCT system. This offers several advantages:

- Unified application procedure: One text for all countries of the PCT
- Effort and costs can be saved compared to individual applications.
- Above all, the international application postpones the start of the national phase, which ultimately leaves more time for a balanced decision on how to proceed.

The PCT application simplifies and streamlines the application process in many cases; however, the granting of the patent remains the prerogative of the national designated states. A PCT application has an international phase and a subsequent national phase - read more about this here. It is not unusual for the patent applicant to want to make amendments to the claims during this period. This is possible both in the international phase and in the later national phase, within defined time limits.

Amendments of claims in the international phase

In the international phase of a PCT application, amendments to the claims are possible under Article 19 PCT and also still Article 34 PCT (apart from the correction of obvious mistakes under R. 91 PCT). These possibilities exist independently of each other, one can choose between proceeding under Art. 19 PCT or Art. 34 PCT; but one can also combine both. There are differences, both in terms of requirements and effects.

i) Amendments of claims under Art. 19 PCT

- Amendments are possible once and after receipt of the search report by the applicant; no request for an international preliminary examination is required.
- Time limit for amendments:
Under Art. 19 PCT and R. 46.1 PCT must be filed within 2 months from the date of transmittal of the search report or within 16 months from the (earliest) priority date, whichever is later. The concrete date of transmission of the search report is the date of transmission to the International Bureau and the applicant by the International Searching Authority.
- Subject matter of the amendments: only the claims (not the description or drawings).
- Language requirement: amendments must be filed in the language of publication.
- Effect: Amendments under Art 19 are published with the application.
This may result in a different scope of protection under Art. 29 PCT with regard to an amended scope of the claims compared to the application.
- Confidentiality is provided for amendments under Art 19 PCT until the publication of the international application.
- Amendments under Article 19 PCT cannot be corrected (unless the exception under R. 91.1(b)(iii) PCT applies; cf. R. 91.1(g)(iii) PCT).

(ii) amendments to the claims under Art. 34 PCT

- require the request for an international preliminary examination and
- are possible several times until the international preliminary examination report is drawn up.
- Subject-matter of the amendments: Claims; also description and drawings
- Language requirement: Amendments may be filed in the language of publication or the language of translation under R. 55.2 PCT (R. 55.3).
- There is no publication with the application; therefore confidentiality is given until third parties can inspect the files of the international preliminary examination (see R. 94 PCT).

In practice, this means that if an international preliminary examination has been requested, the time limits for filing amendments to the claims in the international phase do not apply, because then the time restriction is the preparation of the international preliminary examination report.

Without a request for an international preliminary examination, the time limits according to Art. 19 PCT and R. 46.1 PCT must be observed.
If amendments to the claims are to be filed afterward, there is no opportunity to do so until the national phase.

Amendments to the claims in the national phase

An amendment of the claims, the description, and the drawings are possible in the procedure before the designated Offices. In these national phases, too, time limits must be observed when filing amendments, for example, the following time limits:

- Time limit under R. 52(1)(a) PCT: 1 month from the initiation of the national phase, if no separate request for processing/examination of the application is to be filed with the designated Office.
- Time limit under R. 52(1)(b) PCT e.g. in conjunction with R. 161 EPC. R. 161 EPC: The renewed possibility of amendment in the Euro-PCT phase; this is possible within a period of 6 months from notification.
- In addition, amendments in the Euro-PCT phase are possible after receipt of the supplementary European search report (R 137(2) EPC).

Amendments must not go beyond the disclosure content

For all amendments to the claims, it is important to note that these amendments must not go beyond the disclosure content of the international application at the time of filing. This is the rule in almost all PCT-designated states; however, it is also examined by the International Preliminary Examining Authority (see Art. 34(2)(b) PCT).

It should also be borne in mind that amendments of features may introduce new subject matter not only in the amended claim itself but also in the claims as a whole.

Therefore, we advise having the amendments and the claims as a whole drafted or examined by patent attorneys. You are welcome to ask our experienced and internationally networking patent law firm about this, by telephone at +49 (0)69 69 59 60-0 or via

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