Rule 164 EPC provides the applicant with an opportunity to pay upon invitation, within a two-month period, a further search fee for any invention which has not been searched by the (Supplementary) International Searching Authority in the international phase but which the applicant claims upon expiry of the time limit set in the communication under Rules 161 and 162 EPC. This opportunity is available both where a supplementary European search is to be carried out (the EPO was not the (S)ISA) and where the supplementary European search is dispensed with (the EPO acted as (S)ISA). The further search fees are not subject to the fee reduction under Article 153(7) EPC (see point 5.9.017), which applies only to the search fee payable under Rule 159(1)(e) EPC. Moreover, any further search fees cannot be validly paid until an invitation pursuant to Rule 164 EPC has been issued. The inventions for which a further search fee is paid will be searched by the EPO. The search will not be based on any amendments filed in response to an invitation to pay search fees.

If the applicant uses automatic debiting, all search fees to be paid under Rule 164 EPC will be automatically debited on the last day of the two-month period set in the invitation. Therefore, if the applicant does not wish to pay any or some of the fees, he must notify the EPO accordingly.

The further search fees must be paid within the non-extendable two-month time limit set in the invitation. This time limit is excluded from further processing, but re-establishment of rights may be requested. 

If the applicant disagrees with the finding of lack of unity made by the search division or the examining division, he may request the examining division to review this finding and to refund the search fees paid. 

An invention that has not been searched by the EPO cannot be prosecuted in examination. Therefore, if the applicant does not take the opportunity to pay search fees under Rule 164 EPC, he will be requested by the examining division to delete any unsearched subject-matter. Any searched or unsearched invention which is not prosecuted in the examination proceedings may be pursued in a divisional application.