Number of tiers

Law No. 165 of November 3, 2017 (Rosatellum law)

See the analysis of the Italian 2017 electoral reform in English here. 

232 members are elected  using FPTP; 386 members are elected using List PR with closed lists; and 12 members are elected by the Italians abroad using proportional system with open lists. (Since 12 members represent very small portion of the legislation, we don't consider this as a separate tier.)