SDI, or Sistema di Interscambio, is Italy’s central digital platform designed to manage the exchange of electronic invoices between businesses, professionals, and the public administration. Managed by the Italian Revenue Agency (Agenzia delle Entrate), SDI acts as an intermediary that receives electronic invoices from suppliers, checks their compliance with required formats, and forwards them to the intended recipients. The platform ensures that all electronic invoicing processes are secure, standardized, and compliant with Italian regulations. SDI also provides feedback on invoice status, such as acceptance or rejection, and helps combat tax evasion by maintaining a transparent record of transactions. Its use is mandatory for most B2B, B2C, and B2G transactions in Italy.