Create a global variable to hold the value:
In Modules tab of Database window, create a new module called Globals and then, at top enter code:
Public DtHold as Date
Then, in the form's On Current event add code
Me!DateField = DtHold
and
in the form's On Change, add the code
DtHold = Me!Datefield.
You may also be able to do something like this with an unbound hidden field on the form instead of the global variable. You may also have to play with choices of events to get it to work just the way you want it to.