@karanpreetsing , based on article 1, 21 and 22 of the USA-India tax treaty and the IRS rules regarding exempt status of students for five calendar years, your exempt period started in 2014 when you entered USA as a student ( J-1 student) and subsequent F-1 adjustment to F-1 still counted the J-1 period. Thus for US tax purposes your exemption ( from counting days present in the USA ) period terminated at the end of calendar year 2018. 2019 you would be classified as Resident Alien for tax purposes and filing form 1040 ( and not form 1040-NR ).
The tax treaty requires that USA tax authority treat you just like a US student as far as the Social Security/ Medicare taxes go ( because the treaty does not apply to Social Security taxes ) -- so if US students are exempt from Social Security taxes for required training / residency etc., so are you. So if your internship is NOT required by the school, then this income would be taxed like that of an US student and FICA is applicable.
When you fill out your tax return TurboTax will compute the total FICA taxes and you may end up in a "due" situation -- suggest that you file before April 15th. 2020 and therefore avoid any penalty and interest charges. Also make sure that any new employers are aware that you are now a Resident Alien for tax purposes.
Namaste Ji
