Islamabad is 10 hours ahead of Washington, D.C.
There is no standard 8-to-6 overlap. Someone joins early or late.
Practically speaking, Washington, D.C. and Islamabad never share office hours; 10 hours of separation keeps their days apart. To talk live, someone has to flex: an early start in Washington, D.C. can catch the tail end of the day in Islamabad, or the other way round. A quick caveat — Washington, D.C.'s clocks move for daylight saving and Islamabad's don't, so the times here are right for only part of the year.