The filing date of the "first application" must be claimed as a priority, i.e. the application disclosing for the first time any or all of the subject-matter of the European application.

However, in many cases, a European application will claim the right of priority of the date of filing of a previous application. In such cases, it is the priority date (i.e. the date of filing of the previous application) which becomes the effective date for the purposes mentioned in the preceding paragraph.[Art. 89; ]

In this respect see also A‑III, 6.

1.1 Filing date as effective date

1.2 Priority date as effective date

1.3 Validly claiming priority

1.4 First application

1.5 Multiple priorities

If the EPO has established an IPER on the application and the applicant wishes to obtain protection pertaining to claims which were not the subject of this IPER because they were not searched during the international phase in consequence of an objection of lack of unity, the applicant can decide to have such claims searched in response to the invitation to pay additional search fees under Rule 164(2) and choose them for further prosecution.

For international applications entering the European phase with an international search report established by an ISA other than the EPO, a supplementary European search is carried out by the search division in the cases listed in B‑II, 4.3.2.