Rav Moshe Shternbuch: Yeshiva Bochur Giving Tzedoka From His Allowance
If a boy goes to yeshiva and his father gives him money for food, laundry, and his other needs, is he Mechuyav to give tzedoka from the money? Rav Moshe Shternbuch (3:282) says it depends. If the father gives him the money to use for whatever he needs and wants then he must give tzedoka, since giving tzedoka is no less important than any of his other needs.
However if the father specifically tells him what the money is for, then he has no permission to use it for any other purpose including tzedoka. In the latter case he should ask his father's permission to give tzedoka from the money. If his father insists that he should not, it would be Geneiva for him to do so.
Importnat Note: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.