Latest development of European family private international law was marked with the entry into force of two enhanced cooperation regulations in January 2019, one of which is the Council Regulation (EU) 2016/1103 of 24 June 2016 implementing enhanced cooperation in the area of jurisdiction, applicable law and the recognition and enforcement of decisions in matters of matrimonial property regimes (Matrimonial Property Regime Regulation). When it comes to applicable law, the party autonomy, while allowed, is restricted by connexity requirement. The parties are allowed to choose between either the law of the state of the habitual residence of one of the spouses at the time the agreement is concluded or the law of the state of nationality of one of the spouses. Material and formal validity of the choice of law may further subjected to additional rules. The purpose of the presentation is to give an overview of the party autonomy rules concerning applicable law and to inspect the interplay of these rules with the corresponding ones in the Succession Regulation and Rome III Regulation. Particular emphasis will be placed on the issue whether different approach to party autonomy in the Matrimonial Property Regime Regulation compared to the Succession Regulation and Rome III Regulation may cause unfavourable fragmentation in applicable law among issues closely connected to the spouses’ matrimonial property regime such as divorce or succession between spouses.