Do you need a return ticket to enter Indonesia on a social/cultural visa?

Indonesian law does not require a return ticket for the C12 visa. Airlines are not immigration authorities and cannot demand documents beyond what Indonesian law requires. One long-term traveler reports flying to Indonesia for 5 years without ever being asked for a return ticket.

Airlines check for onward tickets because if a passenger is deported, the carrier bears the cost and fine. This means any document showing planned departure may satisfy them — even the cheapest available ticket.

If an airline insists on proof of onward travel, the cheapest option is a ground transport ticket to a neighboring country — bus, train, or ferry — as long as it terminates in another country, not just at an Indonesian border crossing.

Another option is to buy a refundable airline ticket — you won't get a full refund if you cancel, but you'll recover part of the cost. Alternatively, wait until check-in: if they ask, purchase a ticket on the spot at the airport.