Originally Posted by AtlantaTaxExpert
1) The day you convert from the F-1 to the H-1 or H-1B visa, that day to become liable for FICA taxes.
2) You need to show your employer a copy of your visa and show that the work with this employer is related to the field of study that you are pursuing in the U.S. For example, if you are pursuing a masters in software engineering and work on an OPT with a software company, you qualify for the exemption. If, however, you work part-time at a bookstore to earn some extra money to meet expenses, then that income from the bookstore is NOT related to your studies and therefore NOT exempt from FICA taxes.