If you had actually inserted Nov-08 as an Excel date, =H1-1 would have shown
Oct-08, because Nov-08 as a date defaults to 1-Nov-08 and subtracting 1
would give 31-Oct-08.
My guess is that you've got a text string in H1. Check with the formulae
=ISTEXT(H1) and ISNUMBER(H1), and by trying to reformat H1 temporarily as a
different date format such as dd/mmm/yyyy; if the display in H1 doesn't
change, you've got text, not a date.

You confused me a little by referring to the "date format and date
function". If you used the DATE function, could you show us what foirmula
you used?
--
David Biddulph

"alf" wrote in message
...
Hi there!

I inserted a date, for example (Nov-08) in the cell H1 of an excel
sheet. I have used the date format and date function.
Now, I'd like the software to automatically fill out the adjacent cell
(s) [G1] with the previous month(s), e.g.: Oct-08.

I got surprised to see that writing "=H1-1" in cell G1 doesn't make it
happen; it just copies "Nov-08".
Can you give me a help?

Thank you in advance for your support!

best,
alf