Landing time is not departure time
A scheduled arrival does not tell you when you will reach the transport centre. Terminal, immigration queue, baggage and walking time all sit between the flight and the vehicle. Keep an overnight fallback even when the last normal service appears possible on paper.
Night buses are route-specific
Incheon Airport publishes designated late-night routes, terminal boarding locations and fares. A night bus is useful only when its current stop works for the accommodation; it is not a blanket replacement for every daytime airport limousine route.
Build a safe fallback before flying
Save the official airport transport page, the accommodation address in Korean and a realistic taxi budget. Do not depend on an affiliate ticket for a service whose operating window has not been confirmed. Live airport information takes priority over this planning guide.