FYI, all of the details in the post below have been mentioned over time, so if it sounds familiar...
Just a quick note. Dicey does not advocate particularly hard for re-mortgaging the ol' homestead and putting the money in the market. For one thing, in the US, the IRS doesn't just let you write that shit off over and over and over. There are limits to what you can write off. I mentioned it up thread (or on a related thread, who the hell can remember back that far?) and hoped that a CPA might chime in, because I am not a tax professional. Cheddar, where are you when we need you?
For the record, I am NOT against paying off mortgages. I am against pre-paying the cheap, fixed rate mortgage and paying off the mortgage BEFORE all the other steps are fulfilled.
If you pay the mortgage as scheduled, and meanwhile load up on everything else at your disposal (which can include a lot of investment categories, including rental or commercial real estate, or your own business, in addition to equities), you're gonna have a shit-ton of money in investments before you know it. Once you hit your FIRE number, if you want to pay the mortgage off all at once, please go right ahead.
In our case, we sold two mortgaged but equity-rich houses after we hit our number, so being able to pay cash for the new house was absolutely mind-blowing to us. Gotta say, it was damn fun saying, "Nah, we're just gonna skip the mortgage and pay cash" when the lender jerked us around over rates. It was also fun, when my brother's home loan went sideways at the 11th hour, to be able able to lend him the full purchase price of his house for a week-ish (we have the same bank, so we just moved the pea under a different shell) until the lender's problem got resolved.
I hope that's clear. I am aware that others advocate being fully leveraged at all times, which is A-okay if you're comfortable with that, but it's just not my cup of tea. OTOH, our rentals are pretty decently leveraged, and we do not intend to prepay them.