All foreigners visiting India must hold a valid visa. They are very easy to obtain and the application is very straight forward and can easily be obtained from your nearest Indian Mission (Embassy, consulate or high commission). In India, the Foreigners’ Registration Office can help you in extending your visa, in case required.
Foreigners’ Registration Offices
1st Floor, Hans Bhavan, Near Tilak Bridge, New Delhi, India. Pin : 110001
Phone : +(91)-(11)-3319489
This office is open weekdays from 9:30 am to 1:30 pm and 2 pm to 4 pm.

A Tax Clearance Certificate is required, in case your stay is more than 120 days and can be obtained from Central Revenue Building during weekdays.
Central Revenue Building
Income Tax Office (Foreign Section), Vikas Marg, New Delhi, India. Pin : 110001
Phone : +(91)-(11)-3317826
Office is closed for lunch break during 1 to 2 pm.

Always carry photocopies of your important travel documents, which should be kept separate from the originals. A separate visa is required to visit restricted areas like Arunachal Pradesh, Mizoram and Nagaland.