The fee for the international search on an international application is reduced by 75% where the applicant or, if there are two or more applicants, each applicant is
OJ EPO 2020, A4
OJ EPO 2020, A91
R. 18
PCT AG I 5.190
or
The list of these states can be found on the EPO website (epo.org, under Applying for a patent → Fees → International (PCT) fees → Decisions and notices relating to PCT fees → Reduction in international search and preliminary examination fees).