With the exception of visitors from India, Bangladesh and Maldives, all other visitors to Bhutan need a visa.
Indian, Bangladeshis and Maldivian nationals can obtain a visa at the port of entry on producing a valid passport with a minimum of 6 month validity (Indian nationals may also use their Voters Identity Card (VIC)).
All other tourists must obtain a visa clearance prior to travel to Bhutan. Visas are processed through an online system by your licensed Bhutanese tour operator, directly or through a foreign travel agent.
You are required to send the photo-page of your passport to your tour operator who will then apply for your visa. The visa will be processed by the Tourism Council of Bhutan (TCB) once the full payment of your holiday (including a USD $40 visa fee) has been wire transferred and received in the TCB bank account. Once received the visa clearance will be processed within 72 working hours.
At your point of entry you will be required to show your visa clearance letter, the visa will then be stamped into your passport.
- Source: http://www.tourism.gov.bt