The trouble free method to get Nepal visa by in warding at Tribhuban International Airport in Kathmandu or there is provision for border immigration for those trekkers who are ingoing via Tibet and India.  On the other hand citizen from Nigeria, Ghana, Zimbabwe, Swaziland, Cameroon, Somalia, Liberia, Ethiopia, Iraq, Palestine, Afghanistan do not get visa after landing on TIA.  
 
Requirement
One must have valid passport with minimum 6 months of validity
Application form for diplomatic/ official/ tourist visa
Two passport size photographs

Visa fees in cash
Entry points to Nepal
Tribhuvan International Airport, Kathmandu
Kakarvitta, Jhapa (Eastern Nepal)
Birganj, Parsa (Central Nepal)
Kodari, Sindhupalchowk (Northern Border)
Belhiya, Bhairahawa (Rupendehi, Western Nepal)
Jamuna, Nepalgunj (Banke, Mid Western Nepal)
Mohana, Dhangadhi (Kailai, Far Western Nepal)
Gaddachauki, Mahendranagar (Kanchenpur, Far Western Nepal)

Tourist Visa Extension
For the extension of visa meant for 15 days or less is charged with US $ 30 or is equal exchangeable currency and visa extension fee for further 15 days is US $ 2 per day Tourist visa can be extensive for least period of 150 days in a sole visa year (January to December)

Transit Visa
Foreigners, who have come into Nepal for hang about a night in Nepal and enthusiastic to make use of Nepal’s airport aiming to visit other country with plane ticket or foreigners, travelling in accidentally force landed plane for any situation shall be issued transit visa for one day after paying 5 US $ or equal exchangeable currency.

General Information
No foreigner is free to come into and stay in the Nepal with no legitimate visa
Tourist entrance visa can be gained for following duration from Nepalese Embassy/ consulate or further mission offices or immigration offices placed on access points in Nepal.
Once the visa is issued, it cannot make changes, re-validated and visa fees will non refundable
Personal cheque and credit cards are not acknowledged at any way in point of Nepal
Staying in Nepal devoid of passport or a valid visa is punishable offense
Children under 10 years are not charged, however, visa is mandatory
You are suggested to be aware to contact the Immigration Department for visa transfer in case of getting new passport or travel document from your Embassy / Consulate
While trekking Passport and trekking permit are must
Filming in restricted areas or notified areas without permission is strictly prohibited
Respected local tradition, customs, values and sentiments to help them protect local cultures and maintain local.