Here's a fact that surprises most people: a dollar sitting in an offset account and a dollar paid into your loan and available for redraw save you exactly the same amount of interest. To the cent.
Both reduce the balance your lender charges interest on. Both work daily. The interest-saving mechanism is identical.
Which raises an awkward question, because the offset version usually costs more — typically a 0.10–0.30% higher rate, often with a $300–$400 annual package fee on top. On a $600,000 loan that can add up to $20,000 or more over the life of the loan for a feature that saves you no additional interest whatsoever.
So why does anyone choose offset? Because the differences that matter have nothing to do with interest. They're about tax, control, and human behaviour — and depending on your situation, they can be worth far more than the price difference. Or nothing at all.
First, the definitions
Redraw means paying extra money into your loan, beyond the minimum repayments, with the ability to take it back out later. The extra sits inside the loan, reducing the balance.
Offset is a separate transaction account linked to your loan. Money in it doesn't reduce the loan — instead, the lender charges interest only on the difference. A $600,000 loan with $50,000 in offset is charged interest on $550,000.
Same interest outcome. Everything else about them is different.
Difference one: the tax trap almost nobody sees coming
This is the big one, and it only bites years after you make the choice.
When you pay money into your loan, you have legally repaid debt. When you later redraw it, the tax office treats that as new borrowing — and what matters for tax is what the new borrowing is for.
Here's how it plays out. A couple buys an apartment with a $600,000 loan and, being good savers, parks $150,000 extra in it over a few years. Later they upgrade to a house, keep the apartment as an investment, and redraw the $150,000 for the new deposit.
That redraw was borrowing for a private purpose — their own home. So even though the apartment is now a rental, the interest on that $150,000 slice of its loan is not tax-deductible. Ever. They've permanently converted deductible debt into non-deductible debt, and there is no clean way to undo it.
Now run it again with an offset. The $150,000 sat in the offset account; the loan was never paid down. They withdraw their own money for the house, the apartment's full $600,000 loan springs back to charging interest — and because that loan was always for buying the (now) investment property, all of it is deductible.
Same savings, same property, same upgrade. One version preserves the deduction on $150,000 of investment debt; the other destroys it. At a 6% rate and a typical professional's marginal tax rate, that's roughly $3,500–$4,000 of tax benefit per year, every year they hold the property. Over a decade of ownership, the "expensive" offset turns out to be the cheapest thing they ever bought.
If there is any chance your current home becomes an investment property one day — and for upgraders and rentvestors, there usually is — this difference alone can settle the argument. (Tax positions depend on your circumstances; this is general information, so have your accountant confirm yours.)
Difference two: whose money is it, actually?
Money in an offset account is your money, in a deposit account, in your name.
Money in redraw is, legally, the bank's. You've repaid part of the loan, and the redraw facility is a feature the lender lets you use — a feature they can restrict, reduce, or switch off. It's in the fine print of almost every loan contract, and it isn't theoretical: during COVID, one lender abruptly cut customers' redraw limits, absorbing money people thought was their emergency fund into the loan. The outrage forced a reversal, but the legal position didn't change — and a lender is most likely to tighten redraw at exactly the moment you're relying on it, such as when your finances have wobbled.
If the buffer you're building is your genuine emergency fund — the money that lets you sleep — there's a real argument for it sitting in an account you control rather than a facility you're granted.
Difference three: the behaviour gap
On paper, the disciplined saver transfers money into redraw every month and achieves offset-level interest savings at basic-loan prices.
In practice, a full offset account works like an everyday transaction account. Your salary lands in it. Your bills and cards come out of it. Every dollar offsets your loan from the moment it arrives to the moment it leaves — including money that's only passing through. It requires precisely zero effort or discipline, which is exactly why it works.
Redraw needs you to actually do the thing: transfer the money, resist pulling it back out for small stuff, keep the habit going for twenty years. Some people are wired for that. A lot of people who think they are, aren't. The right product is the one that matches how you actually behave, not how you plan to.
So who should pick which?
The basic loan with redraw tends to win when your home will always be your home, you're a disciplined saver, and the loan is at a genuinely lower rate with no fee — you pocket the price difference and lose little you'd actually use. Run your own numbers in the offset vs basic calculator; with savings going into redraw, you'll see exactly what the offset premium costs you.
The offset tends to win when your property might ever become an investment (the tax point), when the buffer doubles as your emergency fund (the control point), when your finances flow through the account anyway (the behaviour point) — or when your balance is large enough to clear the break-even the calculator shows you. And here's the twist worth knowing: some lenders offer offset accounts with little or no rate premium at all, which collapses the whole trade-off. Finding those is rather the point of using a broker.
Either way, the underlying strategy — keeping every spare dollar working against your loan — is the quiet superpower of Australian mortgages. The product choice just decides how much of the benefit you keep, and how much optionality you preserve.
The twenty-minute version
Your loan structure is one of those decisions that's cheap to get right at the start and expensive to fix later — the tax trap especially, since it can't be undone once the redraw's been made. If you're weighing this up, or you set your loan up years ago and the "later" scenario is now approaching, it's worth a proper conversation. Twenty minutes, no cost, and you'll know exactly which side of the trade-off you're on.