Hi,

Yes you can but you don't provide too much help on precisely what you want
to achieve so perhaps you can build on this. Right click your worksheet, view
code and paste this in. As soon as the date in A1 is in the past you get a
popup when you activate the sheet.

Private Sub Worksheet_Activate()
If IsDate(Range("A1").Value) And Range("A1").Value < Date Then
MsgBox "Overdue action " & Range("A1").Value
End If
End Sub

Mike

if you could settle for a color signal, you could use conditional
formatting.........

choose Format, Conditional Formatting:
if cell value            is greater than or equal to
=today()+90  (for example)
then select formatting.

hth
susan