I have been asked if Middle School students who are taking High School math courses can compete in the High School Math Contest.
The answer is: Of course! i welcome the middle schoolers in such classes as Geometry, Algebra-II, or beyond to the High School math contest. They may compete in all the contests, both Individual and Team Tests.
For the purposes of grading, they would be put in with the 9th graders. This makes the "9th Grade" awards category really "9th Grade and Below"