Hello everyone.. I am in difficult situation. Any help will be really appreciated. I started my H1 from Oct 1st 2009 and was on OPT before that. Does that mean that all my income before Oct1 is exempt from tax under India-US tax treaty? How do I file my taxes this year. Also, is it that under India-US tax treaty, entire income is exempt from tax when your on F1 & OPT?
Thanks.

If you are not married, you will file nonresident tax return and Form 8843. Since you have OPT income and are from India, you will get standard deduction as itemized deduction. Your U.S. Tax Return: U.S. Tax Filing Requirements for Non-Residents (http://taxipay.blogspot.com/2008/03/us-tax-filing-requirements-for-non.html)