To apply for a master's degree in finance, all schools can apply with GMAT and some can also apply with GRE. Generally speaking, if your goal is finance or accounting, you can take the GMAT. If you are still considering a master's or doctor's degree in economics, you can consider GRE. Because GRE can cover economics and some finance or accounting.

Whether an economics undergraduate can apply for a master's degree in accounting depends on whether there are accounting-related courses in your economics course, and so does finance. Of course, there are also masters of accounting in the United States designed for non-accounting undergraduates.

Whether it is finance or accounting should be decided as soon as possible according to personal interests and future career planning. I don't know how old your son is this year. You should plan your time.

All right, that's all. Good luck. You can trust me privately if you have any questions.