If you have a bound textbox named ReceivedDate and an unbound textbox named txtDue then you could use the following in your form's current event.
Code:
Dim dtReceived As Date
Dim dtNow As Date
Dim intDiff As Integer
dtReceived = Me.ReceivedDate.Value
dtNow = Date
intDiff = DateDiff("d", dtNow, dtReceived)
MsgBox intDiff
Select Case intDiff
Case Is < 0
Me.txtDue.Value = "Past Due " & intDiff & " Days"
Me.txtDue.ForeColor = 255
Case 0
Me.txtDue.Value = "Due Now!"
Me.txtDue.ForeColor = 255
Case 1 To 20
Me.txtDue.Value = "Due Later " & intDiff & " Days"
Me.txtDue.ForeColor = 0
Case Is > 20
Me.txtDue.Value = "Due Much Later " & intDiff & " Days"
Me.txtDue.ForeColor = 0
End Select