However, it’s not black or white and using some of that spare money to invest along the way will also pay off.
The advertised one-year fixed mortgage rate is 6.7 per cent at the moment, so if you make additional payments on your mortgage, that’s essentially the annual return you’re getting on that money.
Your other options for putting those funds to work will give you a varying range of returns.
Term deposits are a very-low-risk option, and the one-year advertised rate is sitting at about 5.7 per cent right now.
Other assets like managed funds, property and shares will offer much better returns than this, albeit with a higher risk profile and more volatility.
New Zealand shares have delivered an annual return of 9.1 per cent since the NZX 50 index came into being in early 2001.
That’s well above the present cost of borrowing, and much higher than where mortgage rates have been for the bulk of the past 25 years.
It’s an average return over that period, though, and just like any growth asset, those gains don’t come consistently or in a straight line.
The sharemarket has had numerous ups and downs along the way, including three bigger declines of more than 20 per cent.
Those came in the wake of the GFC in 2008 and 2009, again during the Covid-19 pandemic of 2020, and then from early 2021 until the middle of last year, amidst surging inflation and sharp increases in interest rates.
Markets always recover, and in hindsight, we often look back on those difficult periods fondly because of the opportunities we were able to take advantage of.
However, they can be highly disconcerting at the time.
In contrast, the “return” one gets from paying down the mortgage is free of risk, volatility and uncertainty.
If you’re paying that one-year fixed rate of 6.7 per cent, the interest that you’ll save is not at the mercy of economic conditions or market sentiment, it’s guaranteed.
That’s why the textbook, a spreadsheet model and your accountant will usually suggest paying down the mortgage.
There is nowhere in the investment world where you will find a similar return, for zero risk.
But it is never that simple, and that is not always right for all of us.
Doing a bit of investing on the side can be a very good choice for many people. The knowledge gained by educating ourselves about money, shares and financial markets can be invaluable.
When we have skin in the game, we often take a much greater interest in something.
Having a few investment interests, even small ones, might give you the motivation to follow companies more closely, read the business pages more often, and understand how financial markets work.
While you are unlikely to find a better risk and return proposition than making additional mortgage payments, you’ll learn a lot and put yourself in good stead to make better decisions in the future.
Mark Lister is an investment director at Craigs Investment Partners. The information in this article is provided for information only, is intended to be general in nature, and does not take into account your financial situation, objectives, goals, or risk tolerance. Before making any investment decision Craigs Investment Partners recommends you contact an investment adviser.