PF: A potential applicant has their main activity and residence in Country A, but spends each weekend in Country B where they are officially registered. Would they be eligible to apply for a Postdoctoral Fellowship in Country B?

The approach recommended by the Commission in case of “double residency / double activity” is the following:  the country where the researcher has spent the highest cumulative number of months over the reference period should be considered as main residency / main activity country.

If their main residency and main activity is in country A, short stays in country B for private purposes such as weekends should not be taken into account.