Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for processing transit system fares using wireless beacons. One of the methods includes determining, at a receiver device on a passenger transport vehicle, presence of a user device on board the passenger transport vehicle based on a wireless signal emitted by the user device. A user identifier is determined based on the signal emitted by the user device. Ride information associated with the user is determined based at least in part on the determination of presence of the user and based at least in part on determining that the exit criterion is satisfied. The user identifier and the ride information is provided to a payment service system, wherein the payment service system determines a fare based on the ride information and initiates a payment transaction for the fare using a user account identified by the user identifier.