Since an IPER is a non-binding opinion and not a decision, the PCT provides for neither opposition nor appeal against it. Establishment of the IPER is normally the end of the international phase. Any further observations or amendments the applicant wishes to make should therefore be addressed to the elected Offices and not to the IPEA.[Rule 66.4bis; ]

Only when there is an error in the IPER or the IPER has been issued when in fact a second written opinion should have been issued (see GL/PCT‑EPO C‑IV, 2.2) will the file be transmitted to the examiner to decide whether or not to issue a corrected IPER.[GL/ISPE 19.34; ]

In rare cases, the report may be incorrect, for example because it was based on wrong application documents or citations which are wrongly cited or are not comprised in the state of the art or on new documents cited for the first time in the IPER, or because amendments to the claims were overlooked.

In such cases, if there is at least one week before the actual deadline (normally 28 months from the priority date), a new Form 409 is completed with the correct information, and the corrected IPER is sent to the applicant and to WIPO.[GL/ISPE 19.35; ]

In cases where there is less than one week before that deadline, or where the deadline has expired, applicants are called to ask whether they still wish to receive a corrected IPER. If this is the case, a corrected IPER is issued. If the applicant declines to wait for a corrected IPER because of the deadline, Form 428 (minutes of telephone consultation) is completed, indicating the error in the IPER such that, in the regional phase, the applicant may cite the content of this form as evidence, and Form 428 is transmitted for information.

If, despite the applicant's request for rectification, the IPER does not contain any of the defects mentioned above, the formalities officer informs the applicant with a standard letter that the international preliminary examination phase has come to an end. Any further comments may only be addressed to the elected Offices on entry into the national phase.