assuming valid dates in col A, try

=SUMPRODUCT((A1:A40=EDATE(TODAY(),-12))*(A1:A40<=TODAY())*B1:B40)

--
Don Guillett
SalesAid Software

"CDSchomaker" wrote in message
...
I have a database consisting of monthly hours covering the last 10 years.
Occassionally, I need to sum up the hours from the last 12 months. Which
Excel function do I use so that a cell will automatically show the sum of
hours from the last 12 months based on the current date?