I am successfully doing cumulative summing for columns Jan-05 thru Dec-05
based on cell I1 which puts today's date into text by =TEXT(TODAY(),"mmm-yy").

I then use the formula =SUM($O3:INDEX($O3:$Z3,MATCH($I$1,$O$2:$Z$2,0)))
which compares today's date in text vs what I have manually inputted for
month headings in text.

Everything works fine as long as everyone uses an English copy of Excel.
This is not the case in our France location however so when they open up the
spreadsheet, today's date in text is showing as Févr-05 which of course does
not match the English headings of Feb-05. I could of course input the month
headings in text in French so it would match, but then it would not work when
someone with an English copy opens up the spreadsheet.

So I either need a solution to this translation issue, or a new way to do
cumulative summing where I don't need to change dates into text. Any help
would be immensely appreciated.