Hi,

I visited USA from India with a B1 visa last year during sep 2009 and nov 2009.It is a multiple entry visa.
Then again I visited this year in Sep 2010.this time I got the I 94 entry for 6 months.So my stay might get extended till Feb 2011.Does I need to file tax ?

Have you earned any income while residing in the U.S.

If so, you would file as a non-resident alien, filing Form 1040NR or 1040NR-EZ.

Company in India is providing daily allowance for staying here in US.And I am not getting any salary with payslip for staying here.Do file tax for my allowance ?

As long as your income in India-sourced AND you do not exceed 183 days in country in a given year, neither your salary nor the per diem is submject to U.S. taxes.

This is from the tax treaty:
ARTICLE 16. Dependent Personal Services
Income that residents of India receive for personal services performed in the United States as employees (dependent personal services) is exempt from U.S. income tax if the residents meet three requirements.
• They are present in the United States for no more than 183 days during the tax year.
• The income is paid by, or on behalf of, an employer who is not a resident of the United States.
• The income is not borne by a permanent establishment, fixed base, or trade or business the employer has in the United States.