Should You Pay Off Your Mortgage
or Invest? The Australian Answer.

The question everyone googles but nobody agrees on

There's a version of this question that lives in the head of every Australian with a mortgage and a bit of spare cash. You've got $500 left at the end of the month. Do you tip it into the mortgage offset, or do you buy ETFs?

The internet has strong opinions. Finance influencers will tell you to invest because the share market averages 9-10% and your mortgage is only 6%. Mortgage brokers will tell you that paying off your home is the foundation of financial security. Your parents will tell you to pay off the house because that's what they did when rates were 17%.

The problem is that most of this advice comes from the United States, where the financial system is fundamentally different. In the US, mortgage interest is tax-deductible for owner-occupiers, there's no compulsory superannuation, and capital gains are taxed differently. Importing American financial advice into an Australian context is like using a UK road map to navigate Sydney. The roads don't go where you think they do.

The actual maths, simplified

Here's the core comparison, stripped of the noise.

Paying off your mortgage gives you a guaranteed, risk-free, tax-free return equal to your interest rate. If your mortgage rate is 6%, every extra dollar you put in saves you 6% in interest you won't pay. No volatility. No capital gains tax. No management fees. It's the closest thing to a sure bet in personal finance.

Investing in the share market gives you a historically higher but variable return. The ASX 200 has averaged around 9-10% per year over the past decade (including dividends), but that's an average - individual years have ranged from +23% to -37%. You'll also pay tax on dividends and capital gains, and potentially management fees on funds or ETFs.

The spread between the two is narrower than it looks. A 6% guaranteed return from paying off the mortgage compares favourably against a 9% average market return once you subtract tax, fees, and volatility risk. At the top marginal rate of 47%, a 9% gross return on dividends drops to roughly 5.5% after tax - less than the mortgage rate. Franking credits help, but they don't close the entire gap for high-income earners.

The offset account - Australia's secret weapon

Australia has something most countries don't: the mortgage offset account. Money sitting in your offset reduces the loan balance that interest is calculated on, without actually making a repayment. You keep full access to the cash while paying less interest.

That's a big deal. It means you don't have to choose between liquidity and debt reduction. A $50,000 balance in your offset on a 6% mortgage saves you $3,000 a year in interest - tax-free - while the money stays accessible if you need it. No lock-in. No penalty. No tax event when you withdraw.

For most Australians with a mortgage, filling the offset account before investing outside super is the highest-value move available. It's a guaranteed, tax-free, liquid return at whatever your mortgage rate is. The only scenario where it doesn't win is if you're consistently generating after-tax returns above your mortgage rate - and doing it without taking on meaningful risk.

When investing makes more sense

The mortgage-first approach isn't always the right answer. There are situations where investing alongside your mortgage - or even before paying it down aggressively - makes more sense.

Salary sacrificing into super. Concessional super contributions are taxed at 15% instead of your marginal rate. If you're on a 39% or 47% marginal rate, the tax saving alone is substantial - before you even consider the investment returns inside super. This is often the single highest-returning financial move available to high-income Australians.

You've got decades until retirement and a low mortgage rate. If your mortgage rate is 5% and you're 30 with a 35-year investment horizon, the compound growth of a diversified portfolio has historically beaten the mortgage rate over that timeframe. Time smooths volatility. But "historically" is doing a lot of work in that sentence.

You already have an emergency fund and your offset is healthy. Once your offset covers 3-6 months of expenses and your mortgage repayments feel manageable, the marginal value of the next dollar in the offset starts to decline. That's when investing outside super becomes a reasonable conversation.

You want to build an income stream before retirement. Super is locked until preservation age. If you want financial flexibility before then - whether that's semi-retirement, a career change, or simply options - investments outside super give you access when you need it.

When paying off the mortgage wins

Your mortgage rate is above 6%. As rates climb, the guaranteed return from debt reduction becomes harder to beat. At 6.5%, you'd need consistent after-tax investment returns above that level to justify investing instead - and that's a high bar in any market.

You don't sleep well with debt. This matters more than any spreadsheet. Financial decisions aren't purely mathematical - they're psychological. If a large mortgage causes stress, the value of paying it down isn't just financial. Peace of mind has a return that doesn't show up in a compound interest calculator.

You're within 10 years of wanting to be mortgage-free. If your goal is to own your home outright before a specific life event - retirement, kids starting school, a career shift - then focusing repayments is the most predictable path to get there.

CGT changes reduce your after-tax investment returns. If the 50% CGT discount is replaced with inflation indexation or a smaller discount (as is being discussed for the May 2026 budget), the after-tax return on shares and investment property outside super drops. That tips the balance further toward mortgage repayment for new investments.

The realistic answer for most people

For most Australians with a mortgage, the optimal sequence looks something like this:

Want to keep learning?

The mortgage-vs-invest question sits at the intersection of tax, investing, and personal goals. These Australian resources go deeper on all three. No affiliation with PMPC. Just good content from people who know what they're talking about.