@karthikbr_tax , answers to your questions are as follows:
(a)once you have acquired "Resident for tax purposes ", i.e. passed the substantial presence test, it remains in effect till you do something to change that such as visa expiration, leaving the country for good with no intention/plan to return;
(b)When you leave the USA, you should get a sailing permit -- this tells the IRS that taxes on your earned income has been withheld and the immigration people that you are turning in your visa; -- if you do not do this then you remain a "resident for tax purposes" till the system catches up and therefore your world income is within US tax ambit -- you do NOT want that;
(c) tax on Indian income once you have returned to India --- see answer to (b) above
(d) As long as you are presumed to be a "Resident for Tax purposes", you are under the purview of FBAR and FATCA -- therefore it is important to terminate your "Resident for Tax purposes " status as soon as the situation allows.
Question about being on payroll after departure --- treat this as earned while still in the USA for work performed before departure -- just delayed payment --- note that once you are not a resident for tax purposes, the tax rate changes to a flat 30% and must be withheld by the employer -- no Social security and Medicare.
Question on investment income ( dividends, interest etc. ) --- these come under the tax treaty between India and USA -- and depending on the amount may or may not matter. Perhaps we need to talk about this in late 2020.
Is there more I can do for you ?
Namaste ( Gaaru?)
