Tipping Culture in Bhutan

Tipping your personal guide and your driver after the end of your trip is common although there is no set amount for tipping. I guess it really depends on whether or not you are satisfied with their level of service.
Tipping however is not mandatory.

Tourists generally tip the guide and the driver and porters if you are trekking - typically at the end of your trip. If you've had great service, tip generously.