There are many parts of Nepal into which the entry of foreigners is strictly controlled. Many treks that may be suggested on a map are in restricted areas and you either cannot get a permit for those regions or must travel with a liaison officer and pay for a special permit. Some areas specifically closed to foreigners are: Walunchung Gola, Rolwaling and the route to Nangpa La in Khumbu. When planning your trek, assume that these areas will remain closed. Don't count on a last-minute change in the rules. Police checkposts are numerous in the hills and police will turn you back if you try to trek into a restricted area.
Officially there are no longer any restricted areas in Nepal. The immigration office rules now state that "trekkers are not allowed to trek in the notified areas previously known as restricted". Rather than get involved in all this semantic complication, the term "restricted" is used here to refer to places that are closed to trekkers, or open to trekkers only when accompanied by a policeman (a liaison or "environmental" officer).
There are many reasons why the restricted areas exist. In most cases, it is a hangover from a time when the border with China was more sensitive than it is now. Environmental groups, particularly the Nepal Nature Conservation Society, are pressuring the government to keep some places closed for ecological reasons to avoid both cultural and environmental degradation. Because trekkers require assistance when something goes wrong (accident, illness or theft), the government restricts some areas because it doubts that it could provide the security that trekkers need. There are also political reasons for some restrictions. In the 1970s, for example, the Jomsom trek was closed because a major foreign-aided military operation had been mounted there in support of the Khampas in Tibet.
There are many influences on the decision to open or close certain parts of Nepal to foreigners. Recent changes have liberalised both trekking and climbing, and there is considerable pressure to open more areas to trekkers. You should check with a trekking agency or the central immigration office before planning an unusual trek.
Fees for treks to restricted areas range from US$70 per day (with a 10 day minimum) for Mustang to US$90 per week for Humla and Manaslu. You must also pay for a Nepal government official to accompany you throughout the trek.
Permits & Formalities
A trek to a restricted area must be arranged as a fully equipped organised trek through a registered trekking agency using tents, sherpa staff, cooks and porters. The trekking agency arranges the permit through a series of applications, guarantees and letters, a process that requires about two weeks and can be started only 21 days before the arrival of the group. You may not trek alone; there must be at least two trekkers in each group. For some areas there is a limit to the number of trekkers per season. There is no system of advance reservation, and no clear indication of what will happen if the quota is reached the day before you make an application.
Each group is assigned an "environmental officer" who will accompany it during the trek. Despite the fancy name, what you will get is a Nepalese policeman who you must equip, insure and take on the trek. The liaison officer is supposed to handle all the formalities with police and government offices en route.