Use the BeforeInsert event procedure to look up the highest date so far, and
enter the next value.
This example assumes the field/control is named Date1, and comes from
Table1:
Private Sub Form_BeforeInsert(Cancel As Integer)
Dim varResult As Variant
If Not Form.ActiveControl Is Me.Date1 Then
varResult = DMax("Date1", "Table1")
If IsDate(varResult) Then
Me.Date1 = varResult + 1
End If
End If
End Sub
(Note that the code avoids assigning the date if Date1 is the active
control, as it gets really confusing if the user is trying to type something
into that box and another value suddenly shows up.)