1. The account used: one transaction is enough
The notion of use has been clarified by the Conseil d'Etat: a single transaction, incoming or outgoing, during the year is enough to establish use, regardless of the amount. Since 1 January 2019 (2019 Finance Act, art. 7), the reporting obligation further covers all accounts opened, held, used or closed abroad, including accounts that remained dormant during the year, as the administrative guidelines have explicitly confirmed (BOI-CF-CPF-30-20).