Thanks Kurt! I did file 1040NR for 2018 tax year and that comes as a big relief that I didn't mess up. My next question is regarding the FICA tax (Social security and Medicare tax). I was not FICA tax until 1/17/20 paycheck from my employer due to F1 status. I was F1 status from Aug 2014 and my employer file for H1B in April 2019 and H1B petition got approved on 1/7/20. By default h1b start date is October 1st regardless of approval. My question is should I pay IRS back FICA taxes starting from the period of October 2019? How will this get adjusted in 1040 form because for 2019 tax year I have to file as resident?
