Do UC schools count accounting as a math course? What about other schools?

If you are in-state you can see which a-g course requirement Accounting is listed under using this website:
https://hs-articulation.ucop.edu/agcourselist#/list/search/all

At my son’s HS, it was under “g” electives and not Math.

Courses in the “c” subject area recognize the hierarchical nature of mathematics, and advanced courses should demonstrate growth in depth and complexity, both in mathematical maturity as well as in topical organization. Although many schools may follow the traditional Algebra 1 – Geometry – Algebra 2 format (e.g., as outlined in Appendix A of the Common Core State Standards in Mathematics [PDF]), other sequences may treat these topics in an integrated fashion. Combinations of some integrated courses, algebra, geometry and other courses that integrate the Common Core Standards for Mathematical Practice [PDF] for high school, including courses that rigorously apply these standards in the development of career-related skills, can also satisfy the “c” subject requirement. Appendix A of the Common Core State Standards in Mathematics [PDF] offers a starting point for developing courses that align with these standards