Private Sub Worksheet_Change(ByVal Target As Range)
Const WS_RANGE As String = "A:A" '<== change to suit
Const ADD_FORMULA = "=IF(M<rownum><>"""",""Returned"",IF(AND(TODAY()>=K<rownum>+8,M<rownum>=""""),""Require Chasing"",""No Action Required""))"
On Error GoTo ws_exit
Application.EnableEvents = False
If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
With Target
If .Value <> "" Then
Me.Cells(.Row, "N").Formula = Replace(ADD_FORMULA, "<rownum>", .Row)
End If
End With
End If
ws_exit:
Application.EnableEvents = True
End Sub