A passport and an entry visa for Bhutan are must to enter Bhutan. The passport should have the validity of 6 months longer than the visitor’s journey. The entry visa must get pre-approved prior to your arrival to Bhutan. You should provide your tour operator with a quality scan (or photo) of your passport photo page so that they can prepare your Bhutan visa. Please be sure you carry the same passport that you submitted for your Bhutan visa or you will be denied entry.
The cost of Bhutan visas usually depends on your travel package. Otherwise the normal cost is one time US$ 40. After prepayment for your travel arrangements a visa authority letter is issued. After that the actual visa comes into your passport on your arrival at Paro International Airport.
Indians,Bangladeshis and Maldivians need just a travel permit unlike other nationalities.