When you open your main form you can let your form remind you that there are jobs not done past their duedate.
I would do this on the OnCurrent event of your form.
Im guessing your main form has records on it and and ID for every record.
There must me a control on your form that holds that record ID for it to work.
Code:
If DLookup("DateReminder", "YourTable", "ObjectID = fldObjectID") >= Date Then
Me.fldReminder.caption = "Jobs not done"
Else
Me.fldReminder.caption = "Jobs are done"
End If
Im not sure what the setup of your form is, or if you even filter records but tell us more and we will help.