The currency of Indonesia is the rupiah. 1 US$ is approximately 14000 rupiah (IDR). The rupiah is mainly a paper-currency, coins are less-used and sometimes change is not given. Paper money exists in 1000, 2000, 5000, 10000, 20000, 50000, and 100000 rupiah denominations. Coins exist in 100, 500 and 1000 rupiah denominations.

Issues to consider in terms of money in Bukit Lawang:

• Local payments, for food, room, and trips are payable in rupiah cash only (you can book trips on this website using your credit card)
• ATMs usually have a per-transaction limit of 2,500,000rp (machines dispensing 100,000rp notes) or 1,250,000rp (machines dispensing 50,000rp notes) 
• There is usually a maximum daily withdrawal limit from your home bank
• There is no ATM at Bukit Lawang. There is an ATM at Bohorok (12km away by bus), but Visa cards are NOT accepted, only Mastercard. Mastercard cards are not 100% guaranteed to work - there can be problems such as power cuts, or the machine running out of money, or problems with your home bank.
• It is a bad idea to try and buy rupiah outside of Indonesia - the exchange rate will be bad
• If you carry foreign currency it's easy to exchange it in Bukit Lawang, but the rate will be worse (typically 2%) than in Medan. The advantage of bringing your home currency with you to Indonesia is that if it is not finished, you can take it back home with you with no exchange loss. The disadvantage is security concerns, and also the difficulty of getting more money if you did not bring enough cash.
• You can get a cash advance on a credit card at a bank in Medan at no additional charge (your bank at home will charge you). In Bukit Lawang a travel aent offers cash advances subject to a 7% fee
• Most banks in Indonesia do not exchange foreign currency, or only exchange US$. The exception is at the airport.
• The money changers at the bottom of the stairs at Medan airport offer very poor rates - walk to the front of the airport instead, where the bank branches are located
• The money changers in Medan offer the best rates, but they are not always conveniently located
• Foreign currency that is dirty, torn, or has writing on will usually be rejected by moneychangers. Bring clean foreign money only.
• You can try Western Union to send money to yourself in Indonesia. The Western Union office is at Bohorok, at the post office, 12km from Bukit Lawang. They are open on Friday and Saturday mornings, and Monday-Thursday until 3pm. They are closed on public holidays. At the end of Ramadan, this can mean a closure of up to a week. Sometimes the local Western Union office runs out of money. If this happens, try to come back early the next day, or use a Western Union office in the city (Binjai, two hours from Bukit Lawang) instead.

To avoid money issues you can try prepaying the expensive parts of your trip, online, via this website. Also try to carry emergency foreign currency, as well as Indonesian rupiah.