The split of common and individual charges between the units, as well as the calculation methods, are normally set by the co-owners in the building's deed of co-ownership and co-ownership rules.
Viewing and managing repartition keys
In the Properties menu, on the left, open the relevant building.
Stay on the General information tab, then, next to the Units section, click Actions and Repartition keys.
The Repartition keys window shows the current split (for example on a base of 1000) for each unit.
Editing or creating a key
To edit the existing key, click the pencil Update, adjust the values, then save.
To create an additional key, click New repartition.
Remember to save your changes. To close without changing, click Close.