Summing Across Multiple Sheets

Hi,

you may not like this, but ....

You'd make your life a lot easier if you collected all the data in a single sheet, instead of one sheet for each month.
Then you could use a pivot table to sum/slice/dice/categorise by person and time frame.

This would be a lot easier than starting with a (bad (sorry, but true)) spreadsheet design and trying to tack on complicated formulae to enable reporting that could have been simple from the get-go.

check out how to get started with pivot tables here:

http://peltiertech.com/Excel/Pivots/pivotstart.htm

hth