6.6 Priority period 

Where a priority claim's date precedes the European patent application's filing date by more than twelve months, the applicant may be informed by the Receiving Section that their priority claim is considered invalid unless they:

(i)indicate a corrected date lying within the twelve-month period preceding the filing date and do so within the time limit according to Rule 52(3) (see A‑III, 6.5.2) or

(ii)request re-establishment of rights in respect of the priority period and do so within two months of the expiry of the priority period, and this request is subsequently granted (see paragraph below). This only applies where the applicant also filed the European patent application within the same two-month period. 

Where priority is claimed from an application having the same filing date as the European patent application (see A‑III, 6.1), the EPO will inform the applicant that priority cannot be claimed from this application unless the priority date can be corrected (see A‑III, 6.5.2).

Rules 133 and Rule 134 apply to the priority period under Art. 87(1). If the date indicated for the previous application is subsequent to or the same as the filing date, the procedure set out in A‑III, 6.5.2 also applies (with regard to the possibility of correcting clerical or similar errors, see A‑V, 3).

According to Art. 122 and Rule 136(1) re-establishment of rights in respect of the priority period (twelve months according to Art. 87(1)) is possible. The request for re-establishment must be filed within two months of expiry of the priority period (Rule 136(1)) and the omitted act, i.e. the establishment of a filing date for the European patent application, must also be completed in this period (Rule 136(2)). For more details on requesting re-establishment of rights, see E‑VIII, 3.