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Compare an ETF outside super, extra super and a mortgage offset
Same contribution, same horizon, three completely different tax treatments
Your assumption, not a published rate. Assumed fully franked and reinvested — this is what drives the ETF's annual tax drag.
The loan is repaid over this term, so its balance falls — and the offset stops earning on anything above what's left of it.
$261,365 in today's dollars
$252,109 in today's dollars
$217,830 in today's dollars
Totals are in future dollars. Each today's-dollars figure converts its total back over 20 years at 2.5% inflation, so you can read it against what money buys now.
The ETF's capital gains tax, if you sold the whole holding on 2 October 2046
Your mortgage over the same period
Super is shown as a fund balance you cannot access until preservation age, and no tax is deducted from it on the way out — for someone over 60 taking a lump sum from a taxed fund, none is due.
The statutory figures here are the 15% super contributions tax, the 15% tax on a fund's accumulation-phase earnings, the 30% franking rate and the capital gains rules in Treasury Laws Amendment (Tax Reform No. 1) Act 2026. For an ordinary listed-security parcel held by an eligible Australian-resident individual across 1 July 2027, the cost base is generally reset and later growth moves to indexation. From 1 July 2027, the general 50% CGT discount ends for post-reset growth on ordinary assets. Growth up to 30 June 2027 can keep the discount when the real sale meets the 12-month test. Growth, your marginal rate, the dividend yield, the mortgage rate and the years left on your mortgage are your assumptions, not forecasts.
This calculator is not intended to be relied on for the purposes of making a decision in relation to a financial product. Before you make a financial decision, consider obtaining advice from someone who holds an Australian Financial Services Licence. We do not, and we cannot advise you.
This tool compares three common places to put extra money in Australia, using the same monthly contribution and time horizon for each so the comparison is apples-to-apples: an ETF or share portfolio outside super, additional concessional superannuation contributions, and a mortgage offset account.
Each option is taxed completely differently, which is the whole reason to compare them rather than just comparing headline growth rates. An ETF held outside super pays tax on its distributions every year — grossed up for franking credits, taxed at your marginal rate, then reduced by the credit, which is a refund rather than a bill if your rate is below 30% — and then capital gains tax when you sell, which is deducted from the figure shown. Extra super contributions are taxed at 15% going in and the fund pays up to 15% on its earnings after that. Money in an offset account earns no taxable return at all — it reduces the interest you're charged, which is why saving interest at your mortgage rate is the fairest comparison, and why the benefit stops growing once your offset balance reaches what is left of your loan.
The ETF's capital gains tax is where the 2027 reform bites hardest, and it is the reason this comparison is not simply "super wins over long horizons". For an ordinary listed-security parcel acquired on or after 1 July 2027, the general CGT discount is 0% under Treasury Laws Amendment (Tax Reform No. 1) Act 2026. A parcel held across that date is treated differently: its cost base is generally reset and its deferred pre-reset gain can keep the 50% discount. This tool works that out one parcel at a time, on the acquisition date each contribution and each reinvested distribution actually has. Some residential-asset discounts and other statutory exceptions continue.
None of this accounts for market volatility — the model assumes a steady annual growth rate for the whole horizon, which real markets never actually deliver. Treat the output as a comparison of the tax and structural differences between strategies, not a forecast of what any of them will actually return.
This comparator shows the trade-off, not a recommendation — the right answer depends on your numbers, tax rate and how soon you need the money. Super's tax treatment tends to produce a larger balance over long horizons, but it's the least accessible option of the three, so a larger projected figure isn't automatically the better outcome for your situation.
Money in an offset account doesn't earn a taxable return — it reduces the interest calculated on your mortgage. Saving interest at your mortgage rate is economically equivalent to earning that rate tax-free, so that's the fairest comparison to the other options.
No — it amortises on the level repayment implied by your balance, your rate and the years you have left, and that matters more than it sounds. An offset only saves interest on the part of your balance the loan actually covers, so as the loan shrinks the cap falls with it. At the defaults on this page ($400,000 over 25 years at 6.2%, $1,000 a month for 20 years) the loan is down to about $135,197 by year 20, while your contributions alone come to $240,000 — so the offset passes what is left of the loan well before the horizon and part of it earns nothing from then on. The results card names how many months that was true for, and if the loan is discharged inside your horizon it says which month.
Concessional super contributions are taxed at 15% instead of your marginal rate, which is usually a saving for anyone on more than the lowest tax bracket. But you're locking the money away until preservation age, and you're still capped by the annual concessional contributions limit.
Yes, since August 2026. It taxes the ETF's distributions each year, grossed up for franking credits at your marginal rate, and then deducts the capital gains tax on selling the whole holding at the end of your horizon. The gain is worked out one parcel at a time — every monthly contribution and every year's reinvested distribution is its own parcel with its own acquisition date — because the rules turn on that date: an ordinary parcel acquired on or after 1 July 2027 gets no general 50% discount, while a parcel held across that date generally has its cost base reset and can keep the discount on its deferred pre-reset gain. CPI indexation is omitted and would generally reduce the modelled tax, while a possible minimum-tax top-up is also omitted and could increase it. The result is not a lower or upper bound.
Because reinvested distributions form part of it. The distributions are assessed as income in the year you receive them, and the units they buy have a cost base equal to what was reinvested — which is why ETF investors have to keep their reinvestment statements. Ignoring that would tax the same dollars twice: once as income and again as a capital gain. At this page's defaults the cost base comes to $355,386 against $240,000 of contributions, so leaving the reinvestments out would invent $115,386 of tax base that does not exist.
It was removed in August 2026 because it was not really a fourth strategy. It ran the same compounding as the ETF with the tax line deleted, which made it arithmetically the ETF plus all of the ETF's tax, so it came first for every possible input — set the marginal rate to zero and the two were equal to the dollar. Saving a deposit is a genuine question, but it is a savings-goal question rather than a differently-taxed investment: use the Home Deposit Calculator for how long it takes, or the Savings Goals Calculator for a target amount.
Not very, in the sense that markets never grow at a smooth constant rate — some years fall sharply and others rise sharply. The growth rate here is a simplifying assumption to make the strategies comparable, not a prediction of actual year-by-year performance.
Estimates only. Not financial or tax advice. Full disclaimer for your rights and our limitations of liability.
This calculator exists to show you the arithmetic. It applies published Australian rates, thresholds and formulas to the numbers you enter and shows the working, so you can check it. That is all it does — it produces a number and describes what the number is. It does not recommend anything and it holds no opinion about any financial product.
What can move this result
Why these default assumptions are reasonable
This calculator is not intended to be relied on for the purposes of making a decision in relation to a financial product. Before you make a financial decision, consider obtaining advice from someone who holds an Australian Financial Services Licence. We do not, and we cannot advise you.