Chinese embassies will not issue a visa if your passport has less than six months' validity remaining. A valid Chinese visa is required. A Tibet Tourism Bureau (TTB) permit is also required to enter Tibet.
Does Massif Holidays help to arranging Visas in Kathmandu?
Yes, We do arrange all the permit and visa in Kathmandu for your Tibet tour. The Chinese embassy in Kathmandu does not issue visas to individual travellers, only to those booked on a tour and then only group visas. If you turn up with a Chinese visa in your passport, it will be cancelled. We charge around US$80 per person for a visa. US citizens should pay US$150. The visa office at Nepal’s Chinese Embassy accepts applications from 9.45am to 11am Monday to Friday. Note that the main embassy is in Baluwatar, but the separate visa office is in Hattisar. If you are flying from Kathmandu directly to Chinese cities outside Tibet (ie Chengdu or Shanghai), you can enter China on an individual tourist visa issued from abroad. Thus if you want to continue travelling in China after your Tibet trip the easiest thing is to fly from Kathmandu to Chengdu (the plane stops in Lhasa, but TTB permits are not required for transfer) and then fly back to Lhasa with your TTB permit and on your normal Chinese visa.
If you are looking for visa extensions in Tibet, The waishike (foreign affairs) section of the local PSB handles visa extensions. Extensions are very difficult to get in Tibet (and only likely in Lhasa), so don't count on one. It is far easier to extend your visa in other areas of China such as Chengdu, Xining or Xian, where a 30-day extension is commonplace.