Where the date of a priority claim is the same as the date of filing of the European patent application, 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). In the event that 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 effecting correction of clerical or similar errors, see A‑V, 3).
According to Art. 122 and Rule 136(1) it is possible to obtain re-establishment of rights in respect of the priority period (twelve months according to Art. 87(1)). 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 application, must also be completed in this period (Rule 136(2)). For more details on requesting re-establishment of rights see E‑VIII, 3.