I know these numbers were probably off the top of your head, so let's run some real numbers. Let's say a person got their mortgage and started investing from zero in 1992. I chose this year randomly, but wanted them to be invested through the dot com crash and then retire before the 2008/9 crash.

So, if they put 20% down on a $480k home, they would have a principal balance of $400k. If you want a paid off home before you retire early, and let's say you would need 15 years to save 25x your yearly budget, then you better get to making those extra payments - to the tune of an

EXTRA $1075 per month. That's on top of your $1796 per month normal P&I payment just to pay it off in 30 years (this is with a 3.5% mortgage rate, which was UNHEARD of in 1994!! but anything more than ~5-6% and paying down the mortgage is a no-brainer). So, here are the 2 scenario's:

1 = pay normal mortgage payment of $1796 and invest the extra $1075 per month

2 = pay a $2871 mortgage payment to have a paid off house in 15 years

Who gets to an invested portfolio that can support a 4% SWR first? It takes saving ~$24k for 15 years for scenario 2 to have a paid off house and a

$750k portfolio which would support a $30k annual spend at 4% SWR. If you had invested the extra for 15 years you would have a total of

~$1.17MM, but you'd have to withdraw ~$51.5k per year for the next 15 years until you pay off your mortgage. This represents a SWR of 4.4%.

So, if both retired at the end of 2007 (basically right before a downturn) - how would they have fared?

1 = Withdrawing a constant $51.5k a year, with $51.5k withdrawn as cash at the beginning of 2008, at the end of 2015 you'd have ~

$1.248MM2 = Withdrawing a constant $30k a year, with $30k withdrawn as cash at the beginning of 2008, at the end of 2015 you'd have ~

$841kOr, you could pay off the remainder of the mortgage (~$251k) in one swoop at the end of 2007, which would leave you with ~$919k invested. This would give you a ~3.3% SWR going forward.

If you calculated it so that you only worked long enough so that after you paid a lump sum on your mortgage when you retire you would have 25x expenses, you would only have to work ~14 years (1 year less than paying down your mortgage early).