You can use the Alterante Period Range type feature on the Budget vs. Actual Finacial Report Builder.
On the Edit Columns link, select the ff field for each column:
Budget>Amount
Financial> Amount
For each column, select the Alternate Period Range type as either Relative to Report Date and then select on the available period ranges. If these period ranges is not within your scope, then select Relative to Today’s date as the Alternate Period Range Type and select Custom on the Alternate Period Range. You can then now opt to select all the available period that you need to.
You need to do this for all the needed months (period). You also need to create a formula field for each of your budgeted and actual amounts per month. Of course, you need to fill in Column Label to indicate the Months Name (Ex. Actual July 2011, Budget July 2011).