An additional search will sometimes be required either at the first stage of amendment or subsequently. This may arise for a number of reasons. First, an additional search may be necessary where a declaration or a partial search taking the place of the search report under Rule 45 has been issued at the search stage, and subsequently the deficiencies which rendered a meaningful search impossible have been corrected by amendment, or successfully refuted by the applicant. Secondly, an additional search may be necessary where a particular part of the application has not been searched because of an objection of lack of unity of invention, and the arguments put forward by the applicant have convinced the Examining Division that unity is given . Thirdly, an additional search may be necessary where the claims have been so amended that their scope is no longer covered by the original search. Exceptionally, an additional search may be required if the applicant resiles from an acknowledgement of prior art (see IV, 9.8.1) or if the examiner believes that material relevant to obviousness might be found in technical fields not taken into account during the search.

If the application has been filed under the PCT, the search report will be the international search report made under the PCT, which will be accompanied by a supplementary European search report, unless the Administrative Council has decided that a supplementary report is to be dispensed with (see E-IX, 5.4). Both of these reports will have to be considered by the examiner when deciding whether any additional search is required.