We are providing service to US company for first time and want to know what are the taxes involved?
Do I have to fill in any form or does the client fills in a form?

My client gave me W8BEN but my colleague told use W8ECI. I don't know the difference. Any help would be appreciated

Sach

If you are located in India and did NOT do any work within the borders of the United States, you have NO tax obligation whatsoever to the U.S. government, nor to any of the states within the U.S.

I agree with ATE. Your client may want you to fill out Form W-8BEN simply to have documentation that you are a foreign payee.

By filling out W-8ECI, you are indicating that you have taxable activities in the U.S.

Thanks ATE and IT.
What should I fill in Part II - Claim of Tax Treaty Benefits (if applicable)?

Just to confirm, the title to this thread says "to provide service in US" and your description says "providing service to US company." As long as none of the services are being provided IN the U.S. no U.S. tax is due. The fact that the customer is a U.S. customer is not important. On the other hand, if some or all of the services are being performed in the U.S. then the Indian company may be subject to U.S. tax.

As long as no services are being performed in the U.S. then Part II of Form W-8BEN is not applicable.