How important are SAT Subject tests for UCs?
SAT subject tests are recommended but not required, however if you are applying to competitive campuses, the majority of applicants will report SAT subject test scores. Unless your major or the UC campus has no recommendations for SAT subject tests or due financial difficulties you are unable to take them, I suggest you consider taking the recommended subject tests.
UCB/UCLA especially consider them important.
Okay thank you!
SAT subject tests are recommended only for some divisions or majors at UCs: http://admission.universityofcalifornia.edu/freshman/requirements/examination-requirement/SAT-subject-tests/index.html