To Mezonos Maven:
That is all goood while you have no children in yeshiva/BY. Once you take a tuition break/reduction, most people (I imagine) don’t ask their rav what they must give up/ pay tuition before doing whatever it is, from a “treat” for the children to giving to other Mosdos (a famous point by I believe Rav Schwab) or supporting married children.
C”V, someone could be “Asid Litain Alayhem Es HaDin” for all of the teachers that get paid late (or not al all) due to the person who does not pay the tuition they should (even if it is not full).
To nameless: Kol Kavodah is a Maylah. Not paying the tuition you should/could (if you don’t pay full) if you had only tried (while following strict halacha) may very well be Gezel, both from the other parents and from the teachers. It may just be me (an old fuddy-duddy who does not think living off others is the way to go), but I don’t see the question. One side is almost vadai Issurim De’oraysa, the other not.
Of course, if you can pay tuition on only one salary, Kol Hakavod.