Is "do something by date X" inclusive? [duplicate]

Solution 1:

If something is supposed to happen by a certain day, it means it is supposed to happen not later than that, so it includes the day as well.

Solution 2:

It means that at some point on May 30th, the entrants should have been notified.

Technically speaking, notifying them at 23:59:59 on May 30th will suffice to meet that criterion, although for business-related requests most people will operate on "standard working hours", so they probably expect you to notify them while they're at the office (e.g. before 5:00 p.m.) rather than hunting down their home address and waking them up after they've gone to bed.