Sat subject tests that aren't required

If a subject test isn’t required, how much of a difference will it make if I still submit it. I’m talking about colleges like UC Berkeley.

Really depends. Some colleges say it’s “optional”, but in reality it’s pretty necessary. Others truly mean optional when they say that the SAT IIs are optional. I would contact an admissions officer if possible and ask them that directly. I know UVA has recently changed their stance on subject SATs stating they never really had an impact on admissions. That just comes from how they prioritize different parts of your application. From what I’ve gathered in this process so far, colleges really vary in their admissions process more than people think.

It will help. As to how much, I can’t tell.

If you’re doing anything like Engineering, then definitely take Math 2 and Physics/Chem/Bio subject tests.
If you’re majoring in something less competitive like Psychology, then they are not 100% needed.

It depends on the school. UMich does not require SAT2, but they will review the score for the good of the student if submitted. Stanford strongly recommends but not require SAT2, but ~95% of admitted student did submit SAT2 scores. Some schools just make it recommended instead of required so that they can be flexible in recruiting students (e.g. athletes) they really want without violating their rules.

I’d view it like AP tests you may have taken as a Jr or Soph. Did you score a 5? Why not indicate so in your application? Did you get a 2? Ehhhh, maybe not share that one…