Jock,
Copy the code below into the codemodule of the ThisWorkbook object.
If you didn't understand that line, then follow the advice from David McRitchie:
"Unlike standard macros which are installed in standard modules, Workbook Events are installed in
ThisWorkBook in the following manner: F11 (Visual Basic Editor), Get into your project library
(name of your workbook) with Ctrl+R (View, Project Explorer), under the name of your workbook you
see Microsoft Excel Objects, then before Modules you see ThisWorkBook, doubleclick and paste the
code into the code window (F7)."
HTH,
Bernie
MS Excel MVP
Private Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
If Intersect(Target, Sh.Range("C7:C13")) Is Nothing Then Exit Sub
If Target.Cells.Count > 1 Then Exit Sub
If Target.Value <> 1 Then Exit Sub
Application.EnableEvents = False
Target.AutoFill Destination:=Target.Resize( _
Day(DateSerial(Year(Now), Month(Now) + 1, 0)), 1), _
Type:=xlFillSeries
Application.EnableEvents = True
End Sub