Where the EPO has drawn up an international search report (ISR) or a supplementary international search report (SISR), no supplementary European search report is prepared (see the Decision of the Administrative Council of 28 October 2009, OJ EPO 2009, 594, and B‑II, 4.3.1, B‑II, 4.3.2). In these cases, a written opinion of the ISA (WO‑ISA) or a supplementary international search report (SISR) with explanations under Rule 45bis.7(e) PCT and – if the EPO was also IPEA – an international preliminary examination report (IPER) will already have been transmitted to the applicant during the international phase.[Rule 161(1); ]

The applicant is required to respond to the WO‑ISA or SISR prepared by the EPO or, where applicable, to the IPER prepared by the EPO as IPEA. This does not apply where amendments or observations have already been filed which can be considered to be a reply (subject to certain requirements, see E‑IX, 3.3.1). The time limit for response is six months from the invitation according to Rule 161(1) and is not extendable.

The communication under Rule 161(1) is issued promptly after expiry of the time limit for entry into the European phase and is combined with the communication under Rule 162(2) inviting the applicant to pay any claims fees due (see E‑IX, 2.3.8).

Failure to respond to the WO‑ISA, SISR or IPER within this period (by filing amendments and/or comments) leads to the application being deemed to be withdrawn according to Rule 161(1), unless one of the exceptions described in E‑IX, 3.3 applies. Further processing is available for this loss of rights (see E‑VIII, 2). In all cases, the latest filed request on file after expiry of the time limit according to Rule 161(1) will then be taken into account when drafting the first communication (see E‑IX, 4.3.2) or when issuing the invitation under Rule 164(2) (see C‑III, 2.3), provided that the application is not deemed to be withdrawn.

In order to proceed with the examination of the application without having to wait until the expiry of the six-month time limit for response, applicants may explicitly waive their right to a communication pursuant to Rule 161(1) and Rule 162. Provided that, on entry into the European phase, they have also already responded, where required, to the WO‑ISA, the IPER or the SISR and paid the claims fees, no communication under Rules 161 and Rule 162 will be issued (see the Notice from the EPO dated 5 April 2011, OJ EPO 2011, 354). If this is not the case, the communication will be issued and the application will be processed only after expiry of the six-month period, even in the presence of a request under the PACE programme (see E‑VIII, 4).

Where the EPO is an elected Office, the international preliminary examination report and the documents attached to it must be considered in accordance with E‑IX, 4.3.

Where a translation of the priority document is required (see A‑III, 6.8, and F‑VI, 3.4), an invitation to file it according to Rule 53(3) may be sent by the examining division only after the period according to Rule 161(1) has expired (see A‑III, 6.8.2).