If you already have the outline/subtotals/autofilter applied, you can protect
the worksheet in code (auto_open/workbook_open??).

Option Explicit
Sub auto_open()
With Worksheets("sheet1")
.Protect Password:="hi", userinterfaceonly:=True
.EnableOutlining = True
'.EnableAutoFilter = True
End With
End Sub

It needs to be reset each time you open the workbook. (Earlier versions of
excel don't remember it after closing the workbook. IIRC, xl2002+ will remember
the allow autofilter setting under tools|Protection|protect sheet.)

If you're new to macros, you may want to read David McRitchie's intro at:
http://www.mvps.org/dmcritchie/excel/getstarted.htm

CKF wrote:

I have a filter on my worksheet but it becomes inactive if I protect the
worksheet.

--

Dave Peterson