When can the EPO act as designated Office?
Since all EPC contracting states are PCT contracting states, the EPO can act as a designated Office for any EPC contracting state, provided the international application was filed on or after the date on which the EPC entered into force for the state concerned (see point 1.8.001).
If this requirement is not met, it may be that an extension or validation agreement between the EPO and a PCT contracting state was in force on the international filing date that provides for the extension or validation of a European patent application or a European patent to or in the state for which patent protection is sought (see points 2.11.001 ff).
Source: http://www.epo.org/applying/international/guide-for-applicants/html/e/ga_c5_1_2_2.html
Date retrieved: 17 May 2021