The official deadline is midnight on the actual day that the application is due. So if the deadline is November 1, you have until nearly November 2nd to submit the application.
BUT … the Common App is based in the Eastern Time zone, so a student in, say, California, who submits an application at 11 p.m. on November 1 will have a time stamp on that app that says Nov. 2nd due to the time difference.
No student will be penalized for this small discrepancy but, even so, I urge you to try to submit all applications at least several hours (and, better yet, days) before the official deadline. You can’t predict last-minute technical snafus … and the panic they can cause.
This Saturday, with thousands of procrastinators expecting to pull the trigger just before the stroke of midnight (wherever they are) and with a Daylight Savings Time change to boot, I suspect that there may be some wee-hours havoc in many households.