You can start your path in becoming a chartered accountant either after your XIIth or even after completing your graduation or post-graduation. The paths are similar but if you are a graduate or postgraduate.
Foundation course route (after XIIth). To become a chartered accountant, you would need to pass a series of tests, but before taking these set of examinations, you need to pass your XIIth. Once you have cleared your high school, this is the list of exams you need to clear in the given order.