6.6 Priority period 

The priority period under Art. 87(1) is twelve months from the date of filing of the application from which priority is claimed. Rules 133 and Rule 134 apply to the priority period. Where the date of filing of the European patent application is outside the priority period of the priority application, the applicant will be informed by the Receiving Section that their priority claim is considered invalid unless they:

(i)indicate a corrected date lying within the priority period 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 date of filing 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).

If the date indicated for the previous application is subsequent to or the same as the date of filing, 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 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 date of filing 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.