If you've spent any time comparing offset accounts and redraw facilities, you've probably encountered a version of the same explanation. Both reduce the interest you pay. Both give you access to money when you need it. One holds your savings in a linked account; the other lets you pull back extra repayments you've made. Pick whichever one suits your situation.

That comparison is a reasonable starting point. But it stops short of the distinction that actually matters in certain situations — particularly for anyone with an investment property, or anyone who might end up with one down the track.

What an offset account is actually doing

An offset account is a transaction account linked to your home loan. The money in it is yours. It sits beside the loan, not inside it.

Each day, interest is calculated on the loan balance minus whatever is sitting in the offset account. So if your loan is $500,000 and you have $60,000 in the offset, you're only charged interest on $440,000. The loan balance itself doesn't move — you still owe $500,000. The offset is just reducing the figure interest is charged on.

If you withdraw money from the offset tomorrow, the loan balance is unchanged. You've taken your own money back. The loan sits there exactly as it was.

What redraw is actually doing

Redraw looks similar from the outside but works differently at the loan level.

When you make extra repayments, they go into the loan. The balance genuinely reduces. If you've made $60,000 in extra repayments on that same $500,000 loan, your balance is now $440,000. The redraw facility is the mechanism that allows you to pull those funds back out if you need them.

So the day-to-day interest saving can look identical. The access to funds can look identical. But what's happened structurally is not the same. In one case, your money sat beside the loan. In the other, it went into the loan — and you're now re-borrowing it.

Why that distinction matters for tax

In Australia, the interest on a loan taken out to purchase an investment property is generally tax deductible. The rule that determines deductibility is the purpose of the borrowing — not the product type, not the interest rate, not whether the loan is held with a major bank or a smaller lender.

The purpose.

This is where offset and redraw start to tell different stories.

If you have an investment loan and you're parking extra cash in an offset account, the loan's purpose is unchanged. It still exists for the reason it was originally taken out — to fund the purchase of the investment. The interest remains fully deductible against the income the investment generates.

If you've been making extra repayments into an investment loan — reducing the balance — and you later redraw those funds for a personal purpose, the loan's purpose has changed. The original investment borrowing is still there. But the redrawn portion, used for something personal, is no longer investment borrowing. The ATO refers to this as a mixed-purpose loan. The deductibility of the interest is no longer straightforward, and calculating how much you can claim becomes more complicated.

The scenario most people don't anticipate

The situation where this tends to catch people out isn't exotic. It's actually fairly common.

Someone buys a home. They're careful with money — they make extra repayments, and over several years they build up a meaningful amount of available redraw. At some point, they decide to move and keep the original property as a rental. They're aware the loan will now be an investment loan, and they expect to claim the interest.

What they may not have thought through is what happens if they redraw those funds — for moving costs, a deposit on the new home, or anything personal — after the property becomes an investment. The purpose of the redrawn amount is personal. The loan is now partially investment borrowing, partially personal borrowing. The interest they can claim is reduced accordingly, and the calculation gets complicated.

It's worth noting that the same principle applies if the loan was already an investment loan and extra repayments were made into it — any redraw for personal use creates the same mixed-purpose issue.

What this means before you decide

The honest answer is that offset and redraw are appropriate in different situations, and the right one depends on what the loan is for and what it might become.

If you have an investment loan, offset is generally the structure that preserves a clean tax position. The money never enters the loan. The purpose of the borrowing doesn't change. Extra funds can sit in the offset, reduce the daily interest calculation, and be withdrawn without affecting deductibility.

If you have an owner-occupied loan with no plans to convert it to an investment, redraw is a functional and straightforward tool. The tax question doesn't arise in the same way, and making extra repayments into the loan is a sound approach.

The problem tends to emerge when someone applies a redraw strategy to a loan that becomes — or was always — an investment loan, without understanding what happens to the tax position when they access those funds.

The question worth asking first

Before settling on a structure, the more useful question isn't which feature saves more interest. It's: what is this loan likely to be used for, and does that use change at any point?

If the answer involves investment use — now or in the future — the structure that keeps the purpose of the borrowing clean is worth understanding before the decisions are made, not after.