Thank you for your answer. it is really helpful.
After your suggestion, I tried to apply tax treaty but i got an Alert that "This treaty contains time-based retroactive loss provision/s. Exceeding the stay over the treaty maximum time limit will cost loss of benefits retroactive back to the first dollar earned." and in the exemption documents (From 8233) also have shown the message that "The treaty exemption is available only for compensation paid during a period of two years beginning on that date. The entire treaty exemption is lost retroactively if my stay in the US exceeds two years."
This is in case that I have to pay back if I stay over 2-year?
If I have to pay back all 2 years that I was exempted, How to pay back (with or without benefits)
Is it contain any penalties?
