School aid is the one source a Tucson family can usually pair with either path. Because it is a discount on the bill rather than a scholarship from an STO, it fits alongside the ESA or alongside STO awards, as long as the school's own rules allow it. Ask how the school treats ESA families before you apply.
Catholic parish schools typically offer a lower rate for registered, active parishioners, and most church schools in town have a member or congregation rate. Sibling discounts are common at the Christian K-12 campuses on the east side. Larger independent schools, especially the college-prep campuses near Craycroft Road, tend to run formal need-based aid budgets.
Ask early. Many schools award their own aid in spring alongside the STO cycle, and the money is finite. Request the schedule of tuition and fees in writing, and ask which fees an ESA can pay, since registration, required textbooks and uniforms bought through the school are approved uses while some activity fees may not be.
One firm rule: a school or provider may not refund, rebate or share ESA money with a parent. A discount that lowers the invoice is fine; a cash-back arrangement is not.
Combining it with other sources
In Tucson the main decision is ESA or STO for each child each year; the two can't be combined for the same student. A school's own discounts, such as parish, member or sibling rates, lower the bill and can usually sit alongside either path.