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 European patent applicant was the applicant who made the previous application or is their successor in title 

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

(iv)the European patent application concerns 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), the previous application may be an application for a patent, the registration of a utility model or 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 filing date, that date can be used to determine a priority date, irrespective of the outcome (e.g. subsequent withdrawal or refusal) of the application.

As concerns (ii), it is important to note that the transfer of the application including the priority right is distinct from a possible transfer of the priority application and (or of the priority right as such) must have taken place before the filing date of the later European patent application and must be assessed valid under the EPC, regardless of any national laws relevant national provisions. The EPC does not set out any formal requirements for the transfer of the priority right (see G 1/22 and G 2/22). Where the previous application was filed by joint applicants, all of them must be among the later European patent application's applicants or have transferred their rights in the priority application to the later European patent application's applicant (see T 844/18). Proof of the transfer can be filed later. Yet, absent any substantiated indication to the contrary, there is a strong rebuttable presumption under the EPC that an applicant or joint applicants claiming priority in accordance with Art. 88(1) and Rule 52 are also entitled to the claimed priority. The burden of proof is shifted, and the examining division, opponent or third party challenging an applicant's entitlement to priority has to prove that this entitlement is missing. Especially where an international application under the PCT is filed by joint applicants, including the priority applicant, but without naming the priority applicant as applicant for the European designation, the mere fact of the joint filing implies an agreement between the applicants allowing all of them to rely on the priority right unless substantial facts indicate otherwise (see G 1/22 and G 2/22).

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

As concerns (iii), the priority period starts on the day following the first application's filing date (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 patent application, it will be disregarded (see, however, also A‑III, 6.6).