If one is in debt owing money to various government agencies as well as the school his children go to (tuition), is he obligated to take mayser from his income or is the money he’s making obligated to be allocated to those that he owes? Meaning, how can he give mayser if everything he makes doesn’t really belong to him since it is owed to others?
You are right. If you have debts because you don’t have enough money for your expenses, you should minimize the amount of tzedakah that you give. (Together with minimizing your expenses so you can pay off your debts). It doesn’t mean that you shouldn’t give tzedakah at all, however you don’t have to give maser, and you should concentrate on paying your debts.
May Hashem give you ample parnassa for yourself and your whole family.
Sefer Chasidim 454, Tzedakah Umishpat 1-8.