Hi

one way

for Jan Col B use the following formula
=SUMPRODUCT(--(MONTH($A$2:$A$4)=1),B$2:B$4)

this can then be filled across for col C & D
for Feb
use
=SUMPRODUCT(--(MONTH($A$2:$A$4)=2),B$2:B$4)

Etc

alternatively, check out pivot tables - Debra Dalgleish has some good
instructions on her website at www.contextures.com/tiptech.html

Cheers
JulieD

If you format the date column to the form Jan-04 then you can do
Data-Subtotals on each change in the month, or use Autofilter.

Various ways of skinning that cat.

1) SUMPRODUCT Formulas
2) PIVOT Table
3) DATA SUBTOTALS

In this instance I would probably go with 3

Assuming your data starts in Col A with all your dates in ColA and your data
also sorted on ColA.
Insert a new ColA before A, such that it becomes your new Col A.
With your dates now starting in say B2, in A2 put
=YEAR(B2)&TEXT(MONTH(B2),"00") and copy down as far as your data goes.
Select all the data, including Col A and do Data / Subtotals, At each change
in Col A, Sum (Now tick all the boxes you can see)

This allows you to show all the data, or just the summarised data