The text comments on the preliminary question of Kammergericht in Berlin in the case C-558/16, Mahnkopf. It concerns revealing a share in the estate acquired according to § 1371 German BGB - as a result of simplified share of gains (Zugewinnausgleich) - in the European certificate of succession. Determining the boundary between the applicable matrimonial property and the applicable succession law, the author qualifies the share in the estate resulting from § 1371 BGB as a succession law regulation. It should, thus, be revealed in the European certificate of succession. The author criticises at the same time a few assumptions made by the Kammergericht on the European certificate of succession itself