It is customary in Asia to tip service providers, such as waiters, at approximately 10%, depending on the service. Please check the menu of the restaurants and tariff of hotels you are staying. Most restaurants and hotels will charge an additional service charge of 10% + 13% (VAT). The service charge is paid to service providers in hotels and restaurants as tips.
Tipping is expected, though not compulsory, and shows an expression of satisfaction with the people who have assisted you on your tour. There are several times during the trip where there is an opportunity to tip the local guides or drivers we use. You may do this individually, or your tour leader will offer to collect the money and tip as a group. An appropriate amount of tip drivers and local guides ranges from US$1-2 per person per day, depending on the quality and length of the service. For porters on treks, the recommended amount is NPR300-500 (US$4-5) per porter per day; ask your guide for specific recommendations based on the circumstances and culture. The amount is a personal preference; however, as a guideline, US$20-30 per person, per week can be used.