A Nepal 15-day visitor visa is available on arrival at Kathmandu’s Tribhuvan International Airport for US$25. Bring extra cash in USD as well as some photographs of yourself (head shots). Visas are also available for 30 and 90 days for higher fees. Visa fees are waived for nationals of South Asian countries and China. Indian nationals do not need visas.
You can get a tourist visa online and avoid the visa line at the airport. If you apply online, you must do this within 15 days of your visit (that’s the maximum time the application stays in the system). Doing this 10 days or a week in advance should be enough. (Note: when you fill out the form, in the last fields, you should select “Immigration Office” and “TIA”. This means you’ll collect your visa at the Tribhuvan International Airport in Kathmandu.)
If you’re staying the Hotel Yak and Yeti, this is the information you will need for your address in Nepal:
House Number: none, please leave blank (non mandatory field)
Street Name: Durbar Marg
Ward number: 31
Nationals from Nigeria, Ghana, Zimbabwe, Swaziland, Cameroon, Somalia, Liberia, Ethiopia, Iraq, Palestine, Afghanistan, and Syria can not get visa on arrival in Kathmandu and will need to obtain visas from Nepal embassies in their respective countries or the nearest embassy.
For more information check out www.nepalimmigration.gov.np.