By Philippa Billings, Chief Advice Officer, Otivo
Once the mortgage is under control and there's spare money each month, a familiar fork appears, throw it at the loan, or start investing. Both are sound uses of money, which is what makes the choice genuinely hard. The decision turns on a guaranteed saving against an uncertain return, and on how you weigh certainty against growth. Here's how to think it through.
Quick answer
Whether to pay down your mortgage or invest comes down to comparing the certain saving from your mortgage interest rate with the uncertain return from investing, and how much you value flexibility. As at July 2026, paying extra off a mortgage delivers a guaranteed return equal to the interest saved, while investing offers potential growth but no guarantee.
How do the two compare?
At the core, you're comparing two returns of very different kinds. Paying extra off your mortgage earns you a guaranteed return equal to the interest rate you're no longer paying on that amount. Investing offers a return too, but an uncertain one that could be higher or lower over time. So the comparison is a sure thing against a maybe, and the mortgage rate is the number the potential investment return has to beat to make investing the mathematically stronger choice.
Why is paying down the mortgage a guaranteed return?
Because the interest you avoid is money kept, regardless of what markets do. If your mortgage rate is, say, 6%, paying down the balance saves you that 6% with certainty, the equivalent of a risk-free 6% return on that money. Very few investments offer a guaranteed return at that level. That certainty is the mortgage's key advantage, and it's why paying it down is never a bad outcome, even if investing might have done better.
When might investing make more sense?
When the expected return, over a long horizon, is reasonably above your mortgage rate, and you're comfortable with the uncertainty. Investing over many years, including through the tax advantages of super, may offer a higher expected return than a relatively low mortgage rate, though never a guaranteed one. A longer timeframe also gives investments more room to ride out short-term falls. The case for investing strengthens the lower your mortgage rate and the longer your investing horizon.
What else matters besides the numbers?
Quite a lot. Your tolerance for risk shapes how much you value a certain saving over a potentially larger but uncertain gain. Flexibility matters, since money invested is generally more accessible than money paid into a mortgage, which can only be retrieved through redraw or refinancing. And there's peace of mind, some people simply prefer the feeling of a shrinking mortgage, and that's a legitimate factor. The maths narrows the choice, but these softer factors often decide it.
Do you have to choose just one?
No, and many people split the difference. Directing some spare money to extra mortgage repayments and some to investing captures a certain saving and potential growth at the same time, while spreading the bet across both. Where you set that balance depends on your mortgage rate, your timeframe and how you weigh certainty against growth. It's a question well suited to modelling against your own circumstances rather than deciding by rule of thumb.
Frequently asked questions
Is it better to pay off my mortgage or invest?
It depends on comparing your mortgage rate with the return you might earn investing, and on your comfort with risk. Paying down the mortgage is a certain saving, while investing offers potential growth but no guarantee.
Does investing beat paying off the mortgage?
Over a long horizon, investing may offer a higher expected return than a low mortgage rate, but it's never guaranteed, while the mortgage saving is certain. The lower your rate and longer your timeframe, the stronger the case for investing.
Can I pay off my mortgage and invest at the same time?
Yes, and many people do. Splitting spare money between extra repayments and investing captures both a certain saving and potential growth, with the right balance depending on your rate, timeframe and risk comfort.
Where to from here
The choice weighs a certain saving against uncertain growth, and only you can price that trade-off. Otivo, a licensed Australian financial advice platform holding AFSL and Australian Credit Licence No. 485665, offers a retirement planning module that can weigh paying down debt against investing in your overall position, based on your age, income, balance and goals. It helps you see both paths side by side.
Sources
- ASIC MoneySmart — pay off your mortgage or invest — moneysmart.gov.au
Disclaimer
The information in this communication is current as at July 2026 and has been prepared by Otivo Pty Ltd ABN 47 602 457 732, AFSL and Australian Credit Licence No. 485665. This content is general information only and has been prepared without taking into account your objectives, financial situation or needs. It is not personal financial or taxation advice and should not be relied on as such. Before acting on any information, you should consider its appropriateness having regard to your personal circumstances. This material must not be reproduced in whole or in part, or posted on any social media platform, without the prior written consent of Otivo Pty Ltd.