The University of Siena annually publishes the regulations for student fees (https://en.unisi.it/teaching/forms-international-students)

Students enrolled in first cycle, second cycle and long single cycle degree programmes pay annual fees in one or several installments (up to a maximum of four).

The amount of tuition fees is based on both the student’s family income, as declared in the ISEE certification, and on merit (number of credits achieved within August 10th of each year).