Ho Chi Minh City is 11 hours ahead of Washington, D.C.

There is no standard 8-to-6 overlap. Someone joins early or late.

There's no shared 9-to-5 between Washington, D.C. and Ho Chi Minh City; at 11 hours apart, one city's workday is the other's evening or night. Your best bet is one team taking an early-morning or late-evening call — alternating who stretches keeps it fair over time. Remember that Washington, D.C. shifts for daylight saving and Ho Chi Minh City doesn't, so recalculate the overlap after each clock change.