Older guides quote 50, 89 or 150 RSD for line 72, and newsstands at the airport may still offer 'bus tickets'. Since 1 January 2025 the integrated city and suburban network — every bus, tram, trolleybus and BG voz train — is free by city decision, published in the Belgrade Official Gazette on 30 December 2024. The BusPlus/Beograd Plus era is over; nothing needs validating on 72.
Minibus express lines (the E-series and A1, Slavija–airport) were explicitly kept OUT of the free network: they are not part of the integrated system and only paper tickets sold in the vehicle count, 400 RSD for A1. Hop on expecting the free ride and the driver will hand you a ticket and you owe the difference at controller risk.
The fixed airport fare is not negotiated at the window: it is printed per zone at the four e-kiosks (three in baggage reclaim, one in the passenger lounge) before you reach the taxi stand, and the driver must charge exactly that — 3,000 RSD to the core, 2,300 to Novi Beograd, 4 passengers and boot luggage included. Anyone selling a 'taxi' inside the terminal without that slip is off-tariff, and overcharging complaints go to the city inspection, not the driver's office.
BEG is 18 km west of the centre with no rail station — the railway you can reach is Beograd Centar (Prokop), via bus 600 in about 40 minutes or a taxi. The 'Belgrade railway hub' modernization does not include an airport link openable in this decade; pages promising a train from the airport are confusing Prokop with the airport.