A formula can't send data to another sheet, so it would have to be in
the summary sheet bringing it from the other sheet. You probably have a
date column (assume A), a column of names (B) and a column of sale
amounts (C), and let's assume the data starts on row 1, so your formula
would be something like:

=IF(AND(Sheet1!B1="John Doe",MONTH(Sheet1!A1)=9),Sheet1!C1,"")

I suspect you want something different than this, but if so please post
some further details.

Hope this helps.

Pete