Include a YEAR() test as well as your MONTH() test.
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David Biddulph

"Mark" wrote in message
...
I am using the following formula to add up a series of cells by a specific
month. The formula is:
=SUMPRODUCT((MONTH(RBS!A$2:A$1038)=5)*(RBS!N$2:O$1 038))

I now wish to add up the cells by month and year. For example April 08,
May
08 etc.

Thank you.