A mortgage offset account is an everyday transaction account linked to your home loan. Your lender subtracts the balance in that account from your loan balance before it calculates interest, so every dollar sitting there reduces the interest you are charged.
Unlike an extra repayment, the money is still yours to spend. That makes an offset a flexible way to cut interest while keeping a buffer for bills and emergencies.
The catch is cost. Loans with offset accounts can come with higher fees or a slightly higher rate, so an offset only pays when your average balance saves more than it costs (Moneysmart, mortgage offset accounts). This guide covers how the maths works, the habits that make an offset effective and when another option may suit you better.
How does a mortgage offset account work?
Interest on most home loans is calculated daily on the outstanding balance and charged monthly. With a full offset, the lender reduces that balance by whatever is in the linked account on each day.
If you owe $600,000 and have $30,000 in your offset, you are charged interest as if you owed $570,000. Your required repayment usually stays the same, so more of each repayment goes towards the principal. Over time that can shorten your loan term.
Some lenders offer a partial offset, where only a percentage of the balance counts. Check which type you have.
How much interest can an offset account save?
The example below is illustrative arithmetic only, using an assumed rate. It is not a quote or a prediction of what any lender will charge.
| Item | Without offset | With $30,000 average offset |
|---|---|---|
| Loan balance | $600,000 | $600,000 |
| Balance interest is charged on | $600,000 | $570,000 |
| Assumed interest rate | 6.00% p.a. | 6.00% p.a. |
| Approximate interest for the year | $36,000 | $34,200 |
| Approximate saving | $1,800 a year (about $150 a month) |
The simple rule is that the saving is roughly your average offset balance multiplied by your loan rate. Because rates change, so does the benefit. The RBA lifted the cash rate target to 4.60% on 30 September 2026 (RBA, cash rate), and when variable rates rise, each dollar in your offset saves a little more interest.
In practice, real figures depend on daily balances, your rate and how the lender calculates interest. Moneysmart’s pay off your mortgage faster page has a calculator for testing your own numbers.
Which habits make an offset account work harder?
Your average daily balance is what counts, so consistency matters more than one-off deposits.
- Pay your salary straight into the offset. Your balance peaks on payday and stays higher for longer.
- Keep your emergency fund there. It stays accessible but works against your interest bill instead of sitting idle.
- Use a credit card carefully. Some people pay everyday spending on a card and clear it in full from the offset each month, which keeps cash in the offset longer. This only helps if you never carry a balance or pay card interest.
- Time large payments. Pay big bills on their due date rather than early.
- Avoid spreading cash across accounts. Money in a separate savings account isn’t offsetting anything.
Does an offset account cost more?
It can. Some loans with full offset features charge an annual package fee or monthly account fee, and some carry a higher rate than a basic loan with no offset.
As illustrative arithmetic: if your offset balance averages $5,000 and your rate is 6.00% p.a., the offset saves about $300 a year. If the package costs $400 a year, you are behind. If your balance averages $40,000, the same offset saves about $2,400 a year and the fee is easily covered.
Moneysmart’s guide to choosing a home loan encourages you to compare fees and features together, not just the rate.
Offset vs redraw vs extra repayments: which is better?
| Option | How it works | Best for | Watch out for |
|---|---|---|---|
| Offset account | Balance reduces the amount interest is charged on | Keeping savings accessible while cutting interest | Fees or a higher rate; needs a consistent balance |
| Redraw facility | Extra repayments go into the loan and can be withdrawn later | People who want savings slightly harder to reach | Lenders can set minimums, fees or limits on redraw |
| Extra repayments, no redraw | Extra money permanently reduces the loan | Maximum discipline, often with a cheaper basic loan | You can’t get the money back without refinancing |
An offset is usually the most flexible. Redraw or extra repayments can suit you if you prefer a cheaper, simpler loan and don’t need instant access.
What if your home might become an investment property?
This is where the choice between offset and redraw can matter for tax. The ATO’s guidance on interest expenses says whether interest is deductible depends on what the borrowed money is used for.
Money held in an offset hasn’t repaid the loan, while money redrawn from a loan is generally treated as new borrowing for whatever you use it for. If you might rent out your home later, ask your accountant or tax adviser how to structure your savings before you start.
Can you get an offset account on a fixed-rate loan?
Some lenders offer a full or partial offset on fixed loans, but many don’t. If you want the certainty of a fixed rate and the flexibility of an offset, a split loan can give you both: fix one portion and keep the variable portion linked to the offset.
When is it time to review your offset setup?
Review your offset at least once a year and after a big change in income, expenses or plans. Signs it is time to look again:
- Your offset balance is consistently low and you are paying a package fee.
- Your rate has drifted above what new customers are offered.
- You have a fixed loan with no offset and your savings are growing.
- You are planning to buy an investment property or rent out your home.
- Your lender’s offset has limits that don’t suit how you bank.
If your current loan doesn’t have a suitable offset, refinancing may be an option. The refinance home loan Sydney playbook explains how to compare switching costs, and our guide to when refinancing is worth it shows how to work out break-even.
What is the practical next step?
Start by finding your average offset balance over the last few months and multiply it by your rate to estimate the yearly saving. Compare that with any fees you pay. Then test different repayment scenarios in the mortgage repayments calculator.
If you want a second opinion on your loan structure, start an enquiry and we can compare loans with and without offset options for your situation. Any new loan is subject to the lender’s criteria and approval.