Brussels is 6 hours ahead of Washington, D.C.
Best overlap: 8:00 AM to 12:00 PM in Washington, D.C. is 2:00 PM to 6:00 PM in Brussels.
Plan around 8:00 AM to 12:00 PM in Washington, D.C., which is 2:00 PM to 6:00 PM in Brussels, to catch everyone during office hours. Brussels is 6 hours ahead of Washington, D.C., so the practical overlap is about 4 hours — generous enough for meetings, tight enough to be worth booking ahead.