Invalidating your own SAT, or do you mean all SATs? Long term consequences of the former... they might not allow you to take it again, and you might not have what you need to apply for college. You could still go, but you might have to attend a community college first, and scholarships might be less likely. Long term consequences of the latter: Not sure you could actually do this. If you could, some company would just come up with another test. No way are they going to just give up on assessment, but depending on how it was done, it might end up being a better assessment, or perhaps a worse one.