If the applicant proves to the satisfaction of the EPO that the international filing date is incorrect owing to an error made by the receiving Office or that the priority claim has been erroneously considered by the receiving Office or the International Bureau not to have been made, and if the error is an error such that, had it been made by the EPO itself, the EPO would rectify it under EPC law or practice, the EPO must rectify the error and treat the international application as if it had been accorded the rectified international filing date or as if the priority claim had not been considered not to have been made. 

Further, if a receiving Office accords the international filing date on the basis of incorporation by reference (see points 2.4.001 ff), the EPO as designated/elected Office will review this finding in terms of whether the requirements listed in Rule 82ter.1(b)(i) PCT-Rule 82ter.1(b)(iii) PCT have been complied with. In particular, the EPO will consider whether the element or part incorporated by reference was indeed missing. For instance, where the international application contained a description and a claim or claims on the international filing date, it is not possible to replace these elements with elements from a priority application. It is also not possible to add elements from a priority application if this would result in the international application having, for instance, two (or more) descriptions or two (or more) sets of claims.

If the EPO does not agree with the finding of the receiving Office, it will notify the applicant that it intends to consider the (later) date on which the missing element or part was furnished as the international filing date in the European patent grant procedure. The applicant will be given the opportunity to comment. Further, in the case of missing parts, the applicant may also request that the missing part concerned be disregarded in the European patent grant procedure. In that case, the missing part will be considered not to have been furnished and the EPO will not treat the international application as if the international filing date had been corrected.