As I mentioned a bit last week, were currently debt free except for our mortgage and a student loan with such low interest that it would be financially reckless to pay it back early. The CD in which we were keeping the money to pay for our Prius matured (it was earning a higher percentage return in a CD than we could get on a car loan, so cracking the CD early and paying a penalty just to pay cash seemed like a poor move), so we paid off the full balance of that loan and own both of our vehicles now free and clear (we paid cash for our 2004 Pilot a few months ago).

Right now, were sitting at a decision point. Should we start prepaying significant amounts on our mortgage or should we invest that money elsewhere? I think weve come to a decision, but I also thought walking through our decision-making process.

Our home mortgage sits at about 5.5%. We are looking into refinancing it at 4.75%, but we havent yet fully run the numbers to determine if it would actually save us any money or not because of the cost of the refinancing and because of our intent to pay it off quite early. Were already making payments that amount to about 50% more than what we owe each month.

Our question currently is simple: should we raise those overpayments to 100% or more or should we be investing that extra money into stocks or something else?

If we increased our payments to 100% of what we currently owe each month, we would pay off our mortgage in about seven years. If we exceeded that amount, we would be paying for even fewer years than that.

We view money put into the mortgage as being an investment with a guaranteed return of 5.5%, because thats the amount of annual interest well save by knocking off some principal. If we pay $1,000 early, itll save us $55 in interest this year and about $57 in interest next year and so on.

On the other hand, we could invest that extra mortgage payment each month into something else. We could put it into a savings account that would earn us 1.5% or 2% or so, but it would be very liquid.

We could also invest it in the stock market. It would be very liquid there and it would also have the potential to greatly beat the 5.5% were making on our home loan.

Of course, potential to greatly beat reveals the hard truth. Stock market investing, particularly in the short term, implies quite a bit of risk. 2008 was incredibly painful, for example, as were 2000 and 2001.

The truth is that stocks only pay off as an investment over a long timeframe unless youre banking on some luck.

So, whats our timeframe here? Our plan after our mortgage is paid off is to buy a piece of land in the country and build a house on it (and likely a small barn as well).

If we put the money into our home, we would be completely debt free in five years, buying land a year or two after that, and building a year or two after that. Lets figure five to ten years is our time frame.

Is that long term in terms of the stock market? Sadly, its not. As Warren Buffett so eloquently put it, Only buy something that youd be perfectly happy to hold if the market shut down for 10 years. The simple fact is that over a period of time less than ten years, the stock market is notoriously volatile.

This becomes even more true when you consider that we wont be investing all of it now and just waiting. Instead, wed be investing small amounts regularly over the next several years. Large chunks of our investment would be in stocks for only a year or two.

Thats not the kind of fragile foundation we want for our next home. Wed far rather own our current house free and clear. Its in a good location, rurally placed with great access to the Des Moines metro area, and similar houses have held their value or even gone up over the last several years. We feel, based on the evidence, that well get out of it at least as much as we put into it when we sell it.

Thus, our extra money is going into our mortgage for the time being. I altered our automatic monthly mortgage payment to be 125% more than our normal monthly payment and may yet alter it again (I want to watch our monthly cash flow for a while). This leads us to paying off our house in just a few years and pushing us right towards the country home weve dreamed of.