In Tibet, the only place to exchange foreign currency and
travelers cheques is the Bank of China. The top end hotels in Lhasa
have exchange services but they are only available to guests. The
sensible thing to do is to change as much money in Lhasa as you
think you need. The only other places to change money are Xigaze
and Zham. If you are traveling upcountry, try and get your cash in
small denominations: RMB100 and RMB50 bills are sometimes difficult
to use in rural Tibet. If you don't like the idea of turning up at
the border without Chinese currency you can buy cash RMB from banks
in Hong Kong and the Bank of China in large cities.
Credit Cards
Credit cards are not recommended as a way of payment in Tibet.
Flights and Lhasa hotels cannot be paid using credit cards. The
Lhasa central branch of the Bank of China is the only place in
Tibet which provides credit card advances. A 4% commission is
usually deducted and the minimum advance is normally RMB1200.
Traveler's Cheques
Traveler's cheques are now acceptable at the Bank of China. It
is recommended that you cash them in Lhasa.
Remark: In Tibet coins are not acceptable even for
tipping and sometimes the new version of paper currency is not
recognized and not accepted.
(Tibet Travel Expert)