Bhutanese nationals do not require visa for India. Other country nationals who require visa may approach the Indian Embassy.
One can enter India from Bhutan by land route or by regular Druk Air service from Paro airport for Delhi, Kolkata, Guwahati, Bagdogra and Gaya.
Here are some sites from which you can get more information.
Indian nationals intending to visit Bhutan are required to carry any of the two valid 'Travel Documents' (a) Valid Indian Passport having validity of minimum 6 months; and/or (b) Voter Identity Card, issued by the Election Commission of India. No Visa is required to visit Bhutan.
Indians coming to Bhutan by road are required to obtain an 'Entry Permit' on the basis of valid Travel Document from the Immigration Office of Royal Government of Bhutan at Phuentsholing, located on the Indo-Bhutan border opposite Jaigaon, West Bengal. In case, you are not carrying a valid travel document, you should approach the Indian Consulate Office in Phuentsholing and apply for the "Identification Slip" with proper proof of Indian nationality.
Similarly, Indians coming by air must posses any one of the above mentioned Travel Document and get the Entry Permit at the Paro International Airport.
The 'entry permit' allows an Indian tourist to visit Thimphu and Paro only. However, any tourist going beyond Thimphu and Paro need to acquire a 'special area permit' from the RGoB Immigration Office at Thimphu on any working days (Monday to Friday)
During winter (November to March) the minimum temperature drops to minus 10 in the Thimphu valley. Summers (April-June) are very pleasant. One should avoid traveling during the rainy season (July-September)
Places to visit: Thimphu, Paro, Punakha, Wangdiphodrang, Bumthang. Special permits are however required to visit towns other from Thimphu and Paro.
Distance and driving time of important places in Bhutan
3 hrs. 15 min.
4 hrs. 30 min.
2 hrs. 30 min.
1 hrs. 30 min.
Please visit the following sites for more information about Bhutan: