Only [http://www.taan.org.np/ TAAN] registered trekking agencies in [[Kathmandu]] and [[Pokhara]] can legally organize treks and provide the services of a guide and/or porter with insurance. Be aware that no one else, no hotel, no street broker, no nice person you just met, not even a trekking guide is legally authorized to organize a trek. During the main seasons the agencies run regular group treks, both tea-house and camping styles, and it generally possible to join a group doing a trek of your choice. Independent trekking is quite easy in the main trekking areas.
Trekking Permit '''A trekking permit is required to trek in any part of Nepal. It's called TIMS today. Be sure you have one with you when trekking bit independently or organized. Individual TIMS is obtainable only from Nepal Tourism Board offices and the Trekking Agents Association of Nepal office. Not even Trekking Agents are legally authorized to obtain individual TIMS (even do many small Trekking Agents will offer the individual TIMS). Police check points and Park officers can at any time check your permits.
Restricted areas require
different permits which are obtainable only through the organizing trekking agent for areas like Dolpo, Mustang, Manaslu, Kanchenjunga and other similar areas.
Do not try to bribe officers or police personnel; it might get you in more trouble than you think.