If the receiving Office has specified more than one ISA, the applicant must indicate his choice of ISA in the PCT request (Box No. VII) and in the Fee Calculation Sheet (Box No. 2). Only one ISA may be selected. For example, the EPO may be chosen as ISA for applications filed with the USPTO and for applications in English filed with the JPO as receiving Office. 

Applicants considering their choice of ISA are advised to bear in mind that the EPO will act as an IPEA only if the international search was carried out by the EPO itself or by another European ISA. On 1 January 2020, the EPO, the Austrian, Finnish, Spanish, Swedish and Turkish patent offices as well as the Nordic Patent Institute and the Visegrad Patent Institute were acting as European ISAs (see point 4.1.017).

If the EPO acts as ISA or SISA, no supplementary European search is carried out. Therefore, no search fee will be due on entry into the European phase (see point 5.9.007).

If the EPO acts as IPEA, there is a reduction of 75% of the examination fee in the European phase (see point 5.10.009).