Hello. I am looking into how to file my W-4 as an OPT Visa holder. I am on OPT having completed at least one year of school in the U.S. Under the OPT, I do not need to pay medicare or social security taxes, but I have no way of indicating that on the W-4 form for my employer so they continue to withhold. If there is some additional form that I can attach or some way of indicating that on the form, that work be extremely appreciated.