Your mortgage represents a negative cash flow of $X for N months. The typical mortgage prepayment doesn't reduce your next payment, but does reduce the length of the mortgage. If you look at the amortization table of a 30 year loan, you might see a payment of $1000 but only $50 going to principal. So if on day one you send an extra $51 or so to the bank, you find that in 30 years you just saved that $1000 payment. In effect, it was a long term bond or CD, yielding the post tax rate of the mortgage. Say your loan were 7%. At 7%, money doubles every 10 years or so. 30 years is 3 doubles or 8X. If I were to offer you $1000 and ask for $7500 in 30 years, you might accept it, with an agreement to buy me out if you refinanced. For me, that would be an investment. Just like buying a bond. In fact, there is a real return, as you see the cash flow at the end. The payments 'not made' are your payback.
Those who insist it's not an investment are correct in the strict sense of the word's definition, but pedantic for the fact in practice, the prepayment is a choice to be considered alongside other investment choices. When I have a mortgage, I am the mortgagor, the bank, the mortgagee. Same as a company issuing a bond, the Bank holds my bond and I'm making payments to them. They hold my bond as an investment. There is no question of that. In fact, they package these and sell them as CMOs, groups of mortgages. A pre-payment is me buying back the last coupon on my mortgage. I fail to see the distinction between me 'buying back' $10K in future coupons on my own loan or me investing $10K in someone else's loans.
The real question for me is whether this makes sense when rates are so low. At 4%, I'd say it's a matter of prioritizing any high rate debt and any other investments that might yield more. But even so, it's an investment yielding 4%.
Over the years, I've developed the priorities of where to put new money -
- Matched 401(k) deposits
- High interest credit cards/ debt
- Emergency fund/Roth IRA
- Other retirement savings
- Other regular savings
- Prepay mortgage
The priorities are debatable. I have my opinion, and my reasons to back them up. In general, it's a balance between risk and return. In my opinion, there's something wrong with ignoring a dollar for dollar match on the 401(k) in most circumstances. Others seem to prefer being 100% debt free before saving at all. There's a balance that might be different for each individual.
As I started, the mortgage is a fixed return, with no chance to just get it back if needed. If your cash savings is pretty high, and the choice is a .001% CD or prepay a 4% mortgage, I'd use some funds to pay it down. But not to the point you have no liquid reserves.