How do tuition fees work for non EU master's students?

Short answer: Each university writes its own rules, using one of three systems.

1. Fee based on family income, through an ISEE parificato (M24).
2. A fixed fee for non EU students. Padova charges a fixed fee to non EU students whose family lives abroad, cut to one third for citizens of particularly poor or developing countries (University of Padova). At Ca' Foscari the first instalment is €500 (including the €192 regional tax), and students from low human development countries pay a second instalment of €200 (Ca' Foscari).
3. The maximum fee unless you have a scholarship. At Politecnico di Milano, non EU master's students with a foreign bachelor's pay the full fee unless they receive a Polimi, DSU or other scholarship, even if they submit an ISEE parificato (Politecnico di Milano).

Check deadlines too: Padova charges €218 or €327 for late ISEE or benefit applications (University of Padova).