Private Sub Worksheet_Change(ByVal Target As Range)
    'limit target to a single cell at a time
    If Target.Count > 1 Then Exit Sub
    'limit to specific column
    If Target.Column = 27 Then
        'don't do anything unless target contains something
        If Target.Value <> "" Then
            'prevent changes made by this sub from triggering itself
            Application.EnableEvents = False
            'insert below row of target
            Target.Offset(1).Resize(1, 12).Insert (xlShiftDown)
            're-enable events
            Application.EnableEvents = True
        End If
    End If
End Sub