I am working with my company's US office and I am on L1 Visa . Is my income on L1 visa which is not taxable in US is taxable in India. If so what is the process? Is there any slab for which there is a particular amount of tax to be paid??

If you are in the U.S. for LESS than 183 days, then it is likely that the income earned is tax exempt from U.S. taxes.

Over 183 days, then income and FICA taxes are due.