Clock/Date Equation to Account for Each New Passing Months Cell Budget Totals

I update budgets on my project on a monthly basis and I always have to go into the total column, “1st Qtr. Total (YTD)” and manually change and update the equations in these cell columns to include the beginning of each month’s new budget totals.

Can someone help me with an equation that would automatically check the computer systems clock and when the next new month’s starts it would automatically add in that new month’s budget into the, “1st Qtr. Total (YTD)” column.

So for example, the total column, “1st Qtr. Total (YTD)” automated equation I’m looking for would only total cell contents under “Jan-13”, but would not include the cell contents under “Feb-13” and “Mar-13”. However when were actually in the month of February 2013 this automated equation located in the total column, “1st Qtr. Total (YTD)” would then include the cell contents under both “Jan-13” and “Feb-13”, but exclude the cell contents under “Mar-13”.

Please see the attached example, “Budget Example” for additional information and help.

Thank You.

Garrett