I am trying to do a simple IF statement to change the entry of a cell depending on when a "Date" in another cell reaches a certain date.

e.g. first aid training expiry date = 4/7/2014

I want the expiry cell to change when the Current date reaches that expiry date. to do this. I used =NOW() in a random cell to get the current date/time. but BECAUSE of that. the if statement wont work because this is formula im trying:

a1 is the expiry date
a2 is the =NOW() formula for current date

=IF(a1=a2, "YES", "NO")

but it doesn't recognise it because =NOW() formula?