I have a stupid question.
WHO KNOWS ABOUT “FICA, FED WT, CA ST, CA DIS”?
If I am in the OPT, which tax is available for refund?

You don’t have to pay FICA and Medicare as long as you are in OPT.

Thank you for kind answer.
Do you mean I should pay these of “FED WT, CA ST, CA DIS” except “FICA”. Is it correct?
By the way, do you know why Medicare and social tax is shown up on only W-2 form, not on regular salary statement? I am so confused about this issue. Are the medicare and social tax belong to those tax?

FICA = Social Security Tax.
If none of FICA and SST is in your pay stub, but one of them is showing in W-2, ask HR or accounting dept.
Pay stubs and W-2 should be reconciled.