There is no single correct answer. It turns on four things: your marginal tax rate, how far you are from preservation age, your mortgage interest rate, and how much access to the money you need. Super offers tax concessions but locks the money away. Mortgage repayments give a certain saving and keep flexibility.
This is one of the most searched personal finance questions in Australia and one of the most confidently answered. The confidence is misplaced. The correct answer genuinely differs between two people with identical incomes, because the variables that decide it are not income. Both sides of it sit within advice: superannuation on one, debt and borrowing strategy on the other.
What actually decides this?
Your marginal tax rate. The higher it is, the more a concessional contribution is worth relative to an after-tax dollar going to the mortgage.
How far you are from preservation age. Money going into super at 58 will be accessible in a couple of years. Money going in at 32 will not be touchable for decades. Same contribution, entirely different cost.
Your mortgage rate. Every extra dollar against the loan saves interest at that rate, with certainty. The higher the rate, the stronger the mortgage case.
How much access you need. If there is a realistic chance of needing the money — a business, irregular income, a family situation, an approaching expense — that weighs heavily, because super cannot be tapped when circumstances change.
How does the tax treatment differ?
This is the mechanical part and the source of most of the confusion.
A concessional contribution to superannuation — salary sacrifice, or a personal contribution you claim as a deduction — is taxed inside the fund at a concessional rate rather than at your marginal rate. For someone on a high marginal rate, the difference is substantial. Contributions are subject to an annual cap published by the ATO, and higher earners pay an additional tax on concessional contributions above an income threshold, which narrows the benefit.
A mortgage repayment comes out of income you have already paid full tax on. But the saving it generates — interest you no longer pay — is not taxed. That is the part usually left out. The comparison is not a pre-tax return against a post-tax one; it is a concessionally taxed contribution against a tax-free saving.
Which wins depends on the four variables above, which is why the answer is genuinely individual.
What does locking money away really cost?
Superannuation is preserved. You cannot access it until you meet a condition of release — generally reaching preservation age and retiring. Limited early access exists on severe financial hardship and specified compassionate grounds, but these are narrow and not a general escape.
For someone at 58, preservation is a minor constraint. For someone at 32, it is the dominant consideration, and it deserves to be weighed rather than dismissed as the price of a tax concession.
Where does an offset account fit?
It is frequently the option missing from the framing, and often the relevant one.
An offset account reduces the loan balance interest is calculated on, so the interest saving is the same as making an extra repayment of that amount. The difference is access: offset funds remain available. Money paid directly off the loan may need to be redrawn, and redraw terms vary between lenders and can be changed.
For anyone weighing this question who is also concerned about flexibility, offset often resolves the tension rather than forcing the trade.
Does it have to be one or the other?
No, and treating it as binary is the most common error in how this question gets asked.
Splitting surplus across both is common. It captures some of the tax concession while continuing to reduce debt and keeping some flexibility. The decision is usually the proportion, not the choice.
The proportion is also not permanent. It reasonably shifts over time — as the mortgage shrinks, as income changes, as preservation age approaches, as rates move. Reviewing it every few years is more useful than getting it perfect once, which is part of what ongoing wealth and financial planning is for.
What do people most often get wrong about this question?
Comparing a pre-tax figure to a post-tax one. The most common error. A concessional contribution is measured before tax, a mortgage repayment after it. Comparing the headline numbers without adjusting for that makes super look better than it is.
Ignoring the employer contribution already going in. Superannuation guarantee contributions count towards the concessional cap. Someone on a strong income may have less room for additional contributions than they assume, and exceeding the cap has consequences.
Treating the mortgage rate as fixed. It is not, for most borrowers. A decision that depends heavily on the current rate is a decision worth revisiting when the rate changes.
Forgetting that the loan will end. The mortgage has a finish line. Superannuation does not stop being useful. Someone eight years from paying off a loan is answering a different question from someone twenty-five years out.
Assuming the decision is permanent. It is not. The sensible proportion shifts as income, rates, balances and age change, which is why it is worth reviewing rather than solving once.
What changes the answer as you get older?
The cost of preservation falls as you approach preservation age, which tends to strengthen the super case later in a working life. Mortgage balances are usually smaller by then, so each extra dollar saves less interest. Income is often at its peak, so the marginal rate is at its highest.
Those three shifts move in the same direction, which is why the question is worth revisiting rather than answering once at 35 and never again.
Frequently asked questions
What is the concessional contributions cap?
An annual limit on before-tax contributions to superannuation, including employer contributions. Exceeding it has tax consequences. The current cap is published by the ATO and is indexed over time.
Is salary sacrifice the same as a personal deductible contribution?
Both are concessional and count towards the same cap, but one is arranged through your employer before tax and the other is made personally and claimed as a deduction in your return.
Can I get money out of super if I need it?
Generally not until you meet a condition of release. Limited early access exists on severe financial hardship and specified compassionate grounds, but these are narrow and should not be relied on.
Does an offset account beat extra repayments?
The interest saving is identical for the same balance. The difference is access — offset funds stay available, while extra repayments may need to be redrawn and redraw terms vary by lender.
Do high income earners pay more tax on super contributions?
Yes. Where income plus concessional contributions exceeds a threshold set by the ATO, an additional tax applies to some or all of those contributions, reducing the concession.
Silverloom Advisory Group works through which side of this suits your situation, as part of licensed advice delivered online across Australia. It starts with a free 20 to 30 minute phone call, with no obligation to go further. Book a time that suits you, or get in touch if you would rather ask a question first.
General advice warning. This article contains general information only. It does not take into account your objectives, financial situation or needs, and is not a recommendation to take or not take any particular course of action. Obtain personal advice before acting. Silverloom Advisory Group Pty Ltd is a Corporate Authorised Representative (CAR 1310731) of Core Advice Collective Pty Ltd, AFSL 700341.