If your trek enters a national park such as Langtang or Sagarmatha (Everest), you will need to pay a national park fee. You can pay the fee at the entry to the parks, or in advance from this office, which is located at the Tourist Service Centre, a 20-minute walk from Thamel in Kathmandu. The fee is Rs 3400 for each park. No photo is required. It's closed for up to 10 days over the Dasain holiday period.