Nationals from Bangladesh, India and Maldives do not need a visa. Everyone else needs to arrange a visa before arriving.
To obtain a Bhutanese visa, you need to book a tour. Prices start at US$250 per day per person and can take up to one month to process. When entering Bhutan, you receive a visa for only 2 weeks from Paro airport.
The Kingdom Of Bhutan Visitor Information
Bhutan missions