6.1 General remarks 

(i)the previous application was filed in or for a state or WTO member recognised as giving rise to a priority right in accordance with the provisions of the EPC (see also A‑III, 6.2);

(ii)the applicant for the European patent was the applicant, or is the successor in title to the applicant, who made the previous application; 

(iii)the European application is made during a period of twelve months from the date of filing of the previous application (see, however, A‑III, 6.6); and

(iv)the European application is in respect of the same invention as the invention disclosed in the previous application (see also A‑III, 6.4 and F‑VI, 1), which must be the "first application" (see F‑VI, 1.4 and 1.4.1).

As concerns (i) above, the previous application may be an application for a patent or for the registration of a utility model or for a utility certificate. However, a priority right based on the deposit of an industrial design is not recognised (see J 15/80).

So long as the contents of the previous application were sufficient to establish a date of filing, it can be used to determine a priority date, irrespective of the outcome (e.g. subsequent withdrawal or refusal) of the application.

As concerns (ii) above, the transfer of the application including the priority right (or of the priority right as such) must have taken place before the filing date of the later European application and must be a transfer valid under the relevant national provisions. Where the previous application was filed by joint applicants, all these applicants must be amongst the applicants of the later European patent application or have transferred their rights in the priority application to the applicant of the later European patent application (see T 844/18). Proof of the transfer can be filed later.

However, in the case of joint applicants filing the later European patent application, it is sufficient if one of the applicants is the applicant or successor in title to the applicant of the previous application. There is no need for a special transfer of the priority right to the other applicant(s), since the later European application has been filed jointly. The same applies to the case where the previous application itself was filed by joint applicants, provided that all these applicants, or their successor(s) in title, are amongst the joint applicants of the later European patent application.

As concerns (iii) above, the priority period starts on the day following the date of filing of the first application (Art. 4C(2) Paris Convention and Rule 131(2)). Accordingly, where a priority claim relates to an application filed on the same day as the European application, it will be disregarded (see, however, also A‑III, 6.6).