For trekking in Lower Mustang, TIMs and ACAP permits are required and can be obtained by the trekker themselves from the Nepal Tourism Board in Kathmandu and the Tourist Office in Pokhara. For RAP (Restricted Area Permit) individual trekkers cannot obtain the RAP permit for Upper Mustang themselves. The special permits for restricted areas like Upper Mustang in Nepal are indeed issued exclusively through the Department of Immigration under the Ministry of Home Affairs. Trekking companies play a vital role in facilitating this process for trekkers. For more information please click the following link Permit .