I am a contractor on OPT and have been in the US for less than 5 years. My country of citizenship is India.

My employer has deducted FICA and CA Dis from my pay. I know that I need not pay these taxes as I am on OPT - can I ask for a refund now or wait till I file my taxes next year ?

Do I need to pay CA Dis also ?

You must pay the California disability.

Ask your employer to Refund the FICA tax.