Tourist visas are issued either for one month or for six months. In case of the former, entry into India has to be within one month from the date of issue. This visa is not available by post. The latter is issued for six months from the date of issue. Fees for both categories are the same, so it is advisable for tourists planning to visit neighbouring countries to ask for the latter. It is preferable for tourists to apply for visa in the country of their residence. 

Tourist visas can be extended by three months at the foreigners' registration office in New Delhi, Mumbai, Calcutta and Madras, or with the Superintendent of Police at any District Headquarters. Four passport size photographs are needed for obtaining a visa. 

If stay in the country exceeds 180 days, then tourists are required to get a tax clearance certificate, available at the foreigners' section of the income tax department in every major city. It is also advisable to keep bank receipts to show that the money has been changed legally. 

Special permits may be required additionally with the visa to visit certain areas of the country. Areas such as parts of Sikkim and the north-east frontier states, and northeast of Himachal Pradesh near the Tibetan border are out of bounds for foreign nationals. In case you need to visit any of these areas, apply for a permit at least four weeks in advance at the Ministry of Home Affairs Foreigners' Section , Lok Nayak Bhavan, Khan Market, New Delhi 110 003. 

Special permits are available at all Indian embassies, consulates and high commissions abroad, including all foreigners' registration offices, immigration offices at main international airports in India.