I updated my projections this morning and decided to figure out the Excel Spreadsheets that you can call up from the Firecalc Results page. The second Firecalc Excel spreadsheet has an error that needs to be fixed. This is the spreadsheet that shows the year by year inputs, data, and formulas. The second table in the spreadsheet is supposed to match the one above, but it is incorrect if Social Security or Pension/Off-Chart spending is entered into the Firecalc calculator.
The problem is with the formula in column J "Starting portfolio". It currently takes the "Ending Portfolio" from the previous year and subtracts inflation adjusted annual "Withdrawals", "Social Security" and "Pension/Off-Chart Spending" income. But SS and Pension income should be added
since it is money coming in, not going out. And Off Chart Spending income is already loaded as a negative, so it should be added
as well. (Complicating things is that the columns marked "Withdrawal Change" actually reflect the Pension/Off-Chart Spending income entered into the calculator.) Anyway, here is the fix that makes everything work correctly:
Change J40 to: =IF(I40<>"",$J$1+I40,$J$1-C40+SUM(D40:H40))
And starting with the next line in column J change to: =IF(I41<>"",T40+I41,T40-C41+SUM(D41:H41)) and so on down column J
Doing this makes the tables match, and then the rest of the formulas make a lot more sense.
With the time I spent resolving this I figured out a couple of other things that might help others make sense of the numbers. The first Excel file shows annual balances before
inflation adjustment to today's dollars. So these figures align with those in the second Excel file column T "Ending Portfolio" for a given input year. However the Firecalc graph shows the year-by-year portfolio balances after
inflation adjustment to today's dollars. So these match the figures in the second Excel file column U "Infl Adj End".
Moderators, please correct me if I got any of this wrong.... but 99.9% pretty sure I got it right.