Visas to Bhutan must be applied and paid for in advance,You should try and make your travel arrangements at least 90 days prior to travel to allow time for all the formalities to be completed.
Everyone traveling to Bhutan requires a visa, except for Indian passport holders. Visas are issued for a duration of two weeks, and cost $20. Your visa will be placed in your passport when you arrive at Immigration control at Paro airport.