Nepal Visa
Basic Requirements 
While Indian nationals are exempt from having to make a visa application to gain entry to Nepal, all other visitors to Nepal must be in possession of a Nepal visa. Nepal visas may be granted for reasons of tourism, business, study or transit. 
Processing Times
The processing time for a Nepal visa takes up to 2 weeks to be processed.  However, this is subject to change.  A Nepal visa’s processing time depends very much on the type of visa, the nationality of the person applying, the time of year and other variables.  Therefore, it is advised that applicants start the application process well in advance of their scheduled trip.

Temporary Nepal Visas
Nepal Tourist Visa
Applicants for the Nepal tourist visa must meet all the necessary requirements, including a current and valid passport. Visitors must also have a return or a through ticket to a country which they have the right of admission or may be required to show evidence of sufficient funds for the duration of their stay in the country.
Nepal tourist visas are granted for a period of 60 days, as a standard.  However, should an applicant be entering the country twice in one calendar year, this entry clearance is reduced to 30 days maximum per visit.  This can be extended to as much as 150 days in total, but Nepal visa legislations means that this is the maximum length of time a national visitor can spend in the country.
Additionally, the Nepal tourist visa does not allow the visa holder to engage in any kind of Nepalese employment during their stay.
Nepal Business Visa
While the same requirements of the Nepal tourist visa apply to applicants for the Nepal business visa, they are also required toshow evidence of their purpose, such as a letter of invitation from the business they will be visiting in Nepal. Additionally, they must be properly licensed by the appropriate Nepalese ministry or department that monitors the operations of the business they will be visiting.
Nepal visas are valid for a period of 90 days, but can be used at any time within 5 years of the visa’s approval. The Nepal business visa grants holders the right to attend meetings, conferences and other business-related activities.  However, the holder is not permitted to be employed in any capacity during their time in  Nepal.
Nepal Embassy Information
Royal Nepalese Embassy London 
12A Kensington Palace Gardens
London
W8 4QU
Telephone:  020 7229 1594 / 6231
Fax:  020 7792 9861
Website:  www.nepembassy.org.uk   Source: visabureau.com