Most Aussies aren't getting the offset account savings they think they are
ASIC reviewed 204,000 home loans and found offset account failures at every major bank — raising a question millions of Australian households haven't thought to ask.
There are 1.8 million Australian households with a mortgage offset account. Many of them have never checked whether it actually works. According to the corporate watchdog, a significant number are right to be worried: the accounts were either never opened, never linked to the mortgage, or left to drift without the bank detecting the fault. The households missed out on the savings. The banks kept the interest.
The failures are trivially detectable — and yet they went undetected
ASIC reviewed 204,000 home loans settled between March and August 2025 across eight banks representing more than 70% of the Australian home loan market. The two most common failures were banks simply not opening the offset account after it had been requested, and accounts being opened but never linked to the mortgage. Both failures are trivially detectable — they show up the moment you check a balance against an expected interest calculation. And yet, across the sector, banks paid out more than $55 million in compensation for offset account failures reported between September 2023 and August 2025. Manual errors by staff were identified as the primary cause. The watchdog found banks struggled to identify failures, were slow to fix them when they did, and did not consistently tell customers what was going wrong.
The mechanics of an offset account are simple enough. The balance held in the account reduces the principal on which mortgage interest is calculated. Hold $100,000 in offset against a $1 million mortgage and you pay interest on $900,000. At a 6% rate, that is $6,000 a year in interest avoided, before tax, without moving the money anywhere. The appeal is obvious.
At 6%, a $100,000 offset balance not working for 12 months is $6,000 in interest that did not need to be paid. At two years, it is $12,000.
But the product has always had more friction than the pitch suggests. Banks typically charge fees to operate offset accounts, sometimes through a higher interest rate on the linked mortgage, sometimes through a direct annual fee, sometimes both. Research from the University of Sydney found that at a 6% mortgage rate, a borrower needs to maintain at least $5,000 in the account for a full year just to break even on a $300 annual fee. For borrowers with smaller savings buffers, or loans with lower rates, the numbers can run the other way. The account costs more than it saves.
The incentive structure explains why banks are not motivated to fix this
That design tension is not accidental. Consider the incentive structure from the bank's side. The offset account competes, internally, with every other deposit product the bank offers. A borrower with $100,000 in offset is a borrower who is not earning interest on that money and therefore not costing the bank spread. But they are also a borrower on whom the bank is charging interest on a smaller balance. From the bank's perspective, the offset account is already a concession. Educating customers to use it more effectively means further compressing the bank's margin on that borrower. There is no mechanism by which a profit-maximising institution is naturally motivated to do that work.
This is not a claim of conspiracy. Banks do not need to actively suppress offset account literacy for the outcome to occur. Complexity is a sufficient explanation on its own. When a product is difficult to audit, carries fees that are hard to isolate, and produces savings that require calculation against a moving mortgage balance, most borrowers will not do the maths. They will trust that the product is working because it was sold to them as working. The ASIC findings suggest that trust has been misplaced in a material number of cases.
What ASIC now wants every offset account holder to do
The watchdog has now formally encouraged every borrower with a mortgage offset account to check three things: whether the account has actually been set up, whether it is linked to the correct loan, and whether it is reducing the interest being charged. That verification can be done by contacting the bank or mortgage broker directly. If the numbers do not add up, the bank is obligated to compensate for losses.
Australians held $349.1 billion in offset balances as of March this year, up 28% in two years. The growth reflects a genuine shift in how households are managing mortgage stress during the rate cycle. That money is doing real work for those whose accounts are correctly configured. For those whose accounts have been sitting idle, broken, or misconfigured since settlement, the compounding cost of that failure is not abstract. At 6%, a $100,000 offset balance not working for 12 months is $6,000 in interest that did not need to be paid. At two years, it is $12,000. Across a large loan, the losses accumulate quickly and quietly, which is precisely the kind of failure that only gets noticed when someone finally does the check.
The prudent read of the ASIC report is not that offset accounts are bad products. For borrowers who can maintain a meaningful balance against the fees, they remain an efficient tool. The prudent read is that no product should be trusted purely on the strength of how it was sold. Check the account. Run the numbers. Do not assume the bank has done that work for you.
Sources
The Conversation — How can I check my offset account is collecting the savings it should?
Frequently Asked Questions
How do I check if my offset account is actually working?
Contact your bank or mortgage broker and ask them to confirm three things: that the offset account has been opened, that it is linked to the correct loan, and that the linked balance is reducing the interest being charged. If you find a discrepancy, the bank is obligated to compensate you for losses.
What happens if my offset account was never linked to my mortgage?
Your mortgage interest will have been calculated on the full loan balance, as if the offset account did not exist. At a 6% rate, a $100,000 offset balance sitting idle for one year costs you $6,000 in interest you did not need to pay, and the bank is required to reimburse that amount.
Why would a bank fail to set up an offset account correctly?
ASIC identified manual staff errors as the primary cause. The failures — accounts never opened, or opened but not linked to the mortgage — are detectable from basic record checks, but banks were found to be slow to identify them and did not consistently notify affected customers.
Are offset accounts worth it for small balances?
Not necessarily. Research from the University of Sydney found that at a 6% mortgage rate, a borrower needs to keep at least $5,000 in the offset account for a full year just to cover a $300 annual fee. Borrowers with smaller savings buffers or lower mortgage rates may pay more in fees than they save in interest.
How much have Australian banks paid out for offset account failures?
Across eight major banks representing more than 70% of the Australian home loan market, more than $55 million in compensation was paid to customers for offset account failures reported between September 2023 and August 2025. ASIC found weaknesses in setup and monitoring practices at all eight institutions.