Customize a report…
1. Go to Reports>Sales>Sales By Customer>Customize Summary.
2. Under Edit Columns, add another column field. Expand Sales folder and click Transaction Total (Revenue) from the list.
3. On the same page, under Report Preview section, click the second column from left.
4. Below that, set
Alternate Period Range Type=Relative to report date
Alternate Period Range =Last Fiscal Year
5. Click the third Column that have just been added.
Alternate Period Range Type=Relative to report date
Alternate Period Range =This Fiscal Year
6. If you wish to have a column for comparison, click the Add Formula Field button on the left portion of the screen.
7. Set the following:
Formula Type = Difference x-y
x=Last Fiscal Year
y=This Fiscal Year
8. Add Report Name and click Save.
You may review the results and customize the report again to the required format.
You can also select specific Periods you want to report on instead of having a year by year comparison, or add more fields for future periods.
hope this helps