When exactly is the deadline?

Colleges and Universities A-Z Harvard University
1

Is it 11:59pm in my timezone or Harvard’s?

2

All indications are that it is Eastern Time. That would be safe.

3

Straight from the common app website: “The application deadline is at 11:59 PM of the stated deadline date. The deadline time is either your local time zone or the school’s time zone, whichever is later.”