IF: In the Guide for Applicants it is described that "unused amounts may be used for other action-related purposes (e.g. to increase the salary of a researcher [...])". Can this be agreed a priori with the host institution and become immediately part of the salary, or is this something that can happen only at the end of the period, provided that the money has not been previously spent?

There is not prescription concerning the period or the modalities of use of the institutional costs unused amounts.

The researcher salary can be increased using this cost category provided these costs are not needed for the research and training activities. The researcher must also agree on the payment modalities.