Sum Part Of Named Range And Pivot Data

I have a named range TOT_BUDGET. We use the current month number to access this range's index for current budgets.

=INDEX(TOT_BUDGET,3)

My quandary is that I need to calculate the YTD budget for one of our dashboards. So, I need to get months 1, 2, and 3 and SUM them. Next month I'll need to get 4 months, etc...

I've looked at SUMIF, but it needs to match against some sort of criteria... I don't have any numeric month labels on the budgets page. I cannot figure out what range/array I would match the month number to.

Now, I know the easy way would be to put a month number at the head of each column, reference that array and do the SUMIF. Blech.

Ideally, I would love to just be able to say =SUM(INDEX(TOT_BUDGET, 1-3)). Is there an Excel function that will let me select an array slice?

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In addition, we are getting the Total Sales number out of Great Plains via an SQL query. We summarize many accounts using a pivot table. We then access this table by using the GETPIVOTDATA function.

GETPIVOTDATA("NETCHANGE",TSALES,"FISCALYEAR",CurrYear,"FISCALPERIOD",CurrMo)

Again, how can I do a total YTD?

Is there a way I can do something similar to a foreach loop in the cell formula? I'd like to avoid macroland with this if possible.