School tuition may even count towards one's maaser if necessary!
The Shulchan Aruch (YD 245:4) writes that parents have an obligation to teach their sons Torah or hire another to teach on their behalf. Many Poskim (Aruch Hashulchan YD 249:10; Chofetz Chaim, Ahavas Chesed 2:19:2) therefore write that as this is an obligatory Mitzva one should not use one’s maaser to pay for it.
The Shevet Halevi (5:133:2) points out that the primary obligation is to teach Torah Shebichsav. As schools today teach Torah Shebaal Peh, one may use one’s maaser if absolutely necessary. R’ Yitzchak Blazer (Shut Pri Yitzchak 2:27) writes that one may use one’s maaser for one’s older children in Yeshiva or Seminary (or even above the age of six).
Some Poskim differentiate between boys and girls tuition. Dayan Weiss (Minchas Yitzchok 10:85) allows one to use one’s maaser to pay for their daughter’s tuition if necessary as one is not obligated to teach them Torah in the same way.
R’ Moshe Feinstein (Igros Moshe YD 2:113) writes that nowadays there is no difference between boys and girls as parents are legally required to send them both to school. While he maintains that one should not use maaser money to pay for one’s child’s education, if one is eligible for a reduction, they should rather pay the full amount, making up the balance out of their maaser.
One who can afford to pay without using one’s maaser should do so. Where school fees are voluntary and pay to subsidize other students too, one may use some of one’s maaser towards the tuition, providing the funds are used for Mitzva related expenses. Either way, one must pay off any school fees before donating money to other charities.