How much time do you need for immigration and connecting flights at Ho Chi Minh City airport (Tan Son Nhat), and is fast track service worth it?

With a 3h10m connection (arriving on an international flight, departing domestically to Phu Quoc), it's usually enough time but tight: immigration plus collecting and re-checking baggage can take 1.5-2 hours during peak hours. In this situation fast track is recommended as a safety buffer.

For an international-to-international transfer (not exiting the airport), 3 hours is usually enough to clear immigration, collect baggage, and re-check in for the next flight — but this doesn't account for possible arrival delays.

Fast track (skip-the-line immigration assistance) may not be necessary for a daytime arrival (e.g. 4pm) if it's not a peak slot — queues at that time are usually not too long. It becomes worth it when many flights land at once.