In the new Single Desk Information System (SSU) architecture, the Third Party Subsidiary Solution (SSET) is the IT component that can be chosen by a Third Party to interact with the SUAP Back Offices. In particular, it is an application that will be provided in subsidiarity to all the Entities that do not have their own Third Party Back Office component or that choose not to equip themselves with a Third Party Back Office component provided by Regions or market operators.

The Third Party Subsidiary Solution will start operating on July 26, 2025, the date on which the Single Desk Information System (SSU) will become functional and operational throughout Italy. SUAP practices, started before that date, will necessarily have to complete their process on the platforms on which they were instructed.