3. Correction of errors in documents filed with the EPO 

Linguistic errors, errors of transcription and mistakes in any document filed with the EPO may be corrected on request under Rule 139, first sentence. Requests for such corrections may be made at any time, provided that proceedings are pending before the EPO (see J 42/92). However, if the error to be corrected concerns items that third parties might expect to be able to take at face value and whose correction would jeopardise their rights, the request for correction must be filed as soon as possible, and at least in time for incorporation in the publication of the European patent application. With regard to correction of priority claims, specific provisions apply with a view to protecting the interests of third parties and allow the applicant to correct priority claims and lay down a time limit for doing so (see Rule 52(3) and A‑III, 6.5.2). This ensures that corrected priority information is available when the application is published. The applicant can only correct the priority claim after this date, in particular after publication of the application, under certain limited circumstances where it is apparent on the face of the published application that a mistake has been made. See J 2/92, J 3/91 and J 6/91 as well as J 11/92 and J 7/94. Each of these decisions indicated situations under EPC 1973 where the requester could correct priority data even though it was too late for a warning to be published with the application. These same situations apply mutatis mutandis under EPC 2000 to the acceptance of requests to correct priority claims after the end of the time limit according to Rule 52(3). Regarding correction of the date indicated for the previous filing, see also A‑III, 6.6.

After expiry of the two-month time limit for correcting erroneous (parts) of the application documents under Rule 56a(1) or Rule 56a(3) (see A‑II, 6), the correction of errors in application documents is governed by Rule 139, second sentence. The allowability of such corrections under Rule 139 is subject to strict requirements.

If the error is in the description, claims or drawings, the correction must be obvious in the sense that it is immediately evident that nothing else could have been intended than what is offered as the correction. Such a correction may be effected only within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relative to the date of filing, from all of the documents as filed (see G 3/89 and G 11/91; see also H‑VI, 2.2.1). The documents to be considered in assessing whether the correction is allowable are those of the application as originally filed, including any late-filed missing parts of the description or missing drawings filed according to Rule 56, or application documents or parts corrected according to Rule 56a, regardless of whether this resulted in a change of the filing date (see A‑II, 5 et seq and A‑II, 6 et seq). However, claims filed after the filing date in response to an invitation according to Rule 58 (see A‑III, 15) cannot be used in assessing the allowability of the request.

It is not allowable under Rule 139 to replace the complete set of application documents (i.e. description, claims and drawings) with other documents that the applicant had intended to file with the request for grant (see G 2/95).

The examining division decides on the request for correction. If such a request is pending before termination of the technical preparations for publication, a reference to it is published on the front page.

In the case of electronic filing of European patent applications, the technical documents (description, claims, abstract and drawings) may be attached in their original format, provided it is one listed in the decision of the President of the EPO dated 14 May 2021, OJ EPO 2021, A42 3 May 2023, OJ EPO 2023, A48. Under this decision, these technical documents may also be attached in a format other than those listed, provided that on filing the application the applicant informs the EPO where it can reasonably acquire the corresponding software. If, on the filing date, the documents making up the European patent application are available both in the format provided by the Online Filing software and in another admissible format in accordance with the above decision, the documents in the latter format can also be used to determine whether a request for correction of the description, claims or drawings is allowable.