All the tourists (except Indian, Bangladeshis and Maldivians) visiting Bhutan must get their Bhutan visa prior to their arrival in Bhutan. There are no systems of issuing visa on arrival in Bhutan.
To get Bhutan visa, every travelers must book their tour with a licensed Bhutanese tour operators and must send a scanned copy of passport photo page (minimum validity of 6 months from the intended tour end date from Bhutan), entire tour money and Bhutan visa fee of US $40 per person in advance.
Tour money is monitored by Tourism Council of Bhutan and tour operators get access to it only after the completion of tour. Once the tour money gets deposited in Tourism Council of Bhutan’s bank account, respective tour operators will apply for your visa through an online system to Tourism Council of Bhutan. Once approved, Tourism Council of Bhutan will issue a visa clearance letter which then will be mail to you by your respective tour operators.
On showing this visa clearance letter at the port of entry, your actual visa will be stamped on your passport.