The RO may notify the ISA of correct part(s) and/or element(s) after the ISA has begun to draw up the international search report. In such cases, the EPO as ISA will invite the applicant to pay an additional fee equal to the search fee within one month of the date of the invitation (Form 208) (Rule 40bis.1 and Article 2(1) RFees).
If the EPO as ISA is notified of correct element(s) and/or part(s) after the search has started but before its completion and the additional fee is paid, the EPO will also complete the already initiated search and issue a non-official international search report and written opinion based on the international application as initially submitted. However, the non-official international search report and written opinion are issued only for the benefit of the applicant and any designated Offices which have given notice under Rule 20.8(b-bis) of an incompatibility. They therefore do not constitute the international search report under Rule 43 and written opinion under Rule 43bis. The applicant thus has no obligation to respond to the non-official written opinion upon entry into the European phase.
Regarding the treatment in the European phase of correct element(s) or part(s) notified after the ISA has begun to draw up the international search report, please see Section C-III, 1.3 in the Guidelines for Examination in the EPO.