Offset Accounts Explained: How They Work, Multiple Offsets, and the Rules
Offset accounts are one of the most powerful - and most misunderstood - features of an Australian home loan. Here's a complete reference covering how interest is calculated, how multiple offsets work, how the benefit compares to a savings account, and why the offset vs redraw decision matters enormously if you own or plan to own investment property.
Last updated: April 2026 · General information only 12 min read
In this article
- What is an offset account?
- How interest is calculated - the daily mechanics
- Why an offset beats a savings account
- Multiple offset accounts
- Offset accounts on fixed rate loans
- Offset vs redraw - what's the difference?
- The critical tax distinction for investors
- If your home might become an investment property
- Fees and when an offset might not be worth it
- Frequently asked questions
What is an offset account?
An offset account is a transaction account linked to your home loan. The balance sitting in that account is subtracted from your outstanding loan balance before interest is calculated - so you only pay interest on the difference. The account works like a normal bank account: your salary can go in, you can pay bills, use a debit card, and withdraw money at any time.
The key distinction from a regular savings account is that instead of earning interest on your savings (which is taxable income), the money in your offset account reduces the interest charged on your loan. The benefit is equivalent in dollar terms - but the tax treatment is fundamentally different, which is one of the main reasons offset accounts are so powerful.
The basic mechanics
| Without offset | With $50,000 in offset | |
|---|---|---|
| Loan balance | $600,000 | $600,000 |
| Offset balance | $0 | $50,000 |
| Interest calculated on | $600,000 | $550,000 |
| Annual interest saving at 6.2% | - | $3,100/yr |
How interest is calculated - the daily mechanics
Interest on an Australian home loan is calculated daily and charged to the loan at the end of each month. This means every dollar in your offset account works for you every single day - not just at the end of the month.
The formula is always the same in structure:
Daily interest = (loan balance − offset balance) × annual interest rate ÷ day count denominator
Example: $600,000 loan at 6.2%, with $50,000 in the offset, using Actual/365:
= ($600,000 − $50,000) × 0.062 ÷ 365
= $550,000 × 0.062 ÷ 365
= $93.42 interest charged that day (vs $101.92 without the offset)
Day count conventions - what the denominator actually is
The "÷ 365" in the formula above isn't universal. Lenders use different day count conventions, and the choice affects how much interest you pay - particularly in a leap year. There are three methods you'll encounter in Australia:
| Convention | How it works | What it means for you |
|---|---|---|
| Actual/365 | Uses actual days elapsed in the numerator, always divides by 365 - even in a leap year | The most common method used by Australian banks. In a leap year, borrowers pay slightly more than their stated annual rate because 366 days of interest accrue but the denominator stays at 365. |
| Actual/Actual | Uses actual days elapsed and divides by the actual number of days in the year - 365 in a normal year, 366 in a leap year | The most mathematically precise method. The effective interest rate matches the stated annual rate exactly, regardless of the year. Used by some lenders and more common in fixed-income markets. |
| Actual/360 | Uses actual days elapsed but always divides by 360 | Less common for Australian home loans but used in some commercial lending. Because the denominator is smaller, borrowers effectively pay a slightly higher rate than the stated annual rate - approximately 1.39% more on a 5% loan. |
For most Australian home loan borrowers, the lender uses Actual/365. Your loan contract or product disclosure statement will specify the convention - it's worth checking, particularly if you're modelling long-run interest savings precisely. The difference between Actual/365 and Actual/Actual is small in any given year - it's a detail worth being aware of, but not one that materially changes the picture in a comprehensive financial plan.
Because interest accrues daily, the timing of your offset deposits matters. Money deposited on the first of the month works for every day of that month. Money deposited on the 28th works for just a few days before the month's interest is charged. This is why routing your salary directly into the offset account maximises the benefit - even if you withdraw it throughout the month for living expenses, every day it sits there it's reducing the daily interest charge.
Your repayments stay the same regardless. The reduction in daily interest means more of each repayment is applied to the principal rather than interest, which is how the offset account progressively shortens your loan term over time.
Why an offset beats a savings account
The comparison between keeping money in an offset account versus a high-interest savings account comes down to three things: the rate, the tax treatment, and the compounding effect.
| High-interest savings account | 100% offset account | |
|---|---|---|
| Effective return | Interest earned on balance (e.g. 5.0%) | Interest saved on loan (e.g. 6.2%) |
| Tax treatment | Interest earned is taxable income | Benefit is not taxable - not income |
| After-tax return (37% tax bracket) | ~3.15% after tax on 5.0% rate | Full 6.2% - no tax adjustment |
| Access to funds | Generally accessible, may have notice period | Immediate - transact like a normal account |
| FCS protection | Yes (up to $250k per ADI - learn about the FCS) | Yes (up to $250k per ADI if a true ADI offset - learn about the FCS) |
| Impact on loan term | None | Reduces loan term - more repayment hits principal |
For someone in the 37% marginal tax bracket, a savings account earning 5.0% effectively returns 3.15% after tax. An offset account saving 6.2% in home loan interest returns the equivalent of 6.2% - tax free. The offset wins by a significant margin, and by more the higher your tax rate.
There are two scenarios where a savings account might win. The first is if your home loan interest rate is genuinely lower than the after-tax savings rate - uncommon in most rate environments. The second is if your savings exceed your loan balance - any funds above the outstanding loan amount are earning you nothing in an offset, since interest is already calculated on zero. In that situation, the surplus is better off somewhere it's actually working.
There's a certain irony worth noting here: the same bank that offers you 4.5% on a savings account will happily charge you 6.2% on your mortgage. That gap - the bank's margin - is exactly the spread you capture by keeping your money in an offset instead of a savings account.
Multiple offset accounts
Many lenders allow borrowers to link more than one transaction account to a single home loan, with the combined balance across all accounts used to calculate interest. This is a genuinely useful feature for households that want to "bucket" their money for different purposes without losing the interest benefit of keeping it all in one place.
For example, you might maintain separate offset accounts for: day-to-day expenses, a holiday fund, an emergency buffer, and a car replacement fund. Each has its own purpose and balance - but all of it offsets the loan simultaneously. The number of offset accounts you can link varies by lender - Macquarie allows up to 10 per variable rate loan account, Westpac allows up to 10 on their Rocket Loan, and most major banks permit at least 4.
Example - $700,000 loan with four linked offset accounts
| Account | Purpose | Avg balance |
|---|---|---|
| Offset 1 | Day-to-day (salary in, bills out) | $8,000 |
| Offset 2 | Emergency fund | $25,000 |
| Offset 3 | Holiday / renovation fund | $15,000 |
| Offset 4 | Tax / annual bills buffer | $12,000 |
| Total combined offset balance | $60,000 | |
| Interest calculated on ($700,000 − $60,000) | $640,000 | |
At 6.2%, the $60,000 combined offset saves approximately $3,720 in interest annually - all while the money remains fully accessible in purpose-labelled accounts.
Offset accounts on fixed rate loans
This is an area where borrowers are frequently caught out. The availability of an offset account depends heavily on whether your loan is variable or fixed rate.
- Variable rate loans: 100% offset accounts are widely available and standard across major lenders. This is the common case.
- Fixed rate loans: most lenders do not offer a 100% offset during a fixed rate period. Some offer a partial offset (capped at a set balance, often $10,000–$20,000). Others offer no offset at all on fixed rate products.
- Split loans (part fixed, part variable): the offset can typically only be linked to the variable portion of the loan.
This is a meaningful factor when comparing fixed and variable rates. A fixed rate that appears cheaper on paper may result in a higher net cost if it comes without an offset account, particularly for borrowers who carry a significant balance in their everyday accounts.
Check the fine print - not all "offsets" are real offsets
Some smaller and non-bank lenders offer a product they call an "offset" that is actually a redraw facility operating under a different name. A true offset account is a separate deposit account held in your name at an Authorised Deposit-taking Institution (ADI), protected under the Financial Claims Scheme up to $250,000. A pseudo-offset that is really a redraw does not carry these protections - your money is technically a repayment on the loan, not a deposit. Always verify the legal structure before signing.
Offset vs redraw - what's the difference?
Both offset accounts and redraw facilities reduce the interest you pay on your loan. In terms of the dollar interest saving in any given month, the result can be identical. But the legal structure, accessibility, and tax treatment are fundamentally different - and those differences matter significantly, particularly for investors.
| Offset account | Redraw facility | |
|---|---|---|
| What it is | A separate deposit account linked to your loan | Extra repayments made directly into the loan that can be withdrawn |
| Where your money sits | In a separate deposit account (yours) | In the loan account (legally repaid to the lender) |
| Access to funds | Immediate - debit card, online, same day | Generally accessible but may require a transfer to a transaction account; some lenders have minimum amounts or delays |
| FCS protection | Yes - up to $250,000 per ADI | No - it is a credit balance in a loan, not a deposit |
| Tax treatment of withdrawals | Neutral - treated as savings, not a new borrowing | Treated as a new borrowing - purpose of the withdrawal determines deductibility |
| Loan balance impact | Loan balance unchanged - offset reduces interest calculation only | Extra repayments reduce the loan balance; redraws increase it again |
| Typical cost | Often requires a loan package with annual fee (~$395/yr); some lenders include at no extra cost | Usually free or lower cost |
The critical tax distinction for investors
For owner-occupiers, the offset vs redraw choice is primarily about accessibility and convenience. For property investors, it can have very significant tax consequences - and choosing the wrong structure can permanently reduce the deductibility of your loan interest.
The ATO's position is clear: the deductibility of interest depends on the purpose of the borrowing, not the security used for the loan or the property the loan is attached to.
How offset protects deductibility
When you put money into an offset account, it sits in a separate deposit account. You haven't made an extra repayment on the loan - the loan balance remains unchanged. When you withdraw from the offset, you're simply accessing your own savings. The ATO does not treat this as a new borrowing, so the purpose of the withdrawal is irrelevant for tax purposes. Withdrawing $50,000 from your offset to fund a holiday does not affect the deductibility of your investment loan.
How redraw can permanently taint a loan
When you make extra repayments into a loan and then redraw them, the ATO treats the redraw as a new borrowing. The interest deductibility of that new borrowing depends entirely on what you use the redrawn funds for. If you redraw from an investment loan to fund a personal expense - a holiday, a car, school fees - that portion of the loan is now considered mixed purpose. The interest must be apportioned between deductible and non-deductible portions, and that split is permanent. Even if you repay the personal portion, you cannot simply reverse the contamination.
Example - how redraw taints an investment loan
Marcus has an investment property loan of $500,000, on which 100% of the interest is tax-deductible. Over several years he makes extra repayments and reduces the balance to $430,000, creating $70,000 of available redraw.
He redraws $30,000 for a family holiday. His loan balance returns to $460,000 - but now only $430,000 relates to the investment purpose. The interest on the $30,000 redraw is not deductible.
From this point, only 93.5% ($430k ÷ $460k) of Marcus's interest is deductible. Future repayments must also be apportioned - he cannot direct repayments only to the non-deductible portion.
If Marcus had used an offset account instead of redraw, withdrawing $30,000 for the holiday would have had zero impact on his deductibility position.
The ATO is actively data-matching
The ATO has conducted a major data-matching program covering residential property loan data from financial institutions between 2021 and 2026, cross-referencing it against tax returns. Borrowers who have redrawn from investment loans and continued to claim full interest deductibility can expect scrutiny. Always consult a registered tax agent before redrawing from an investment loan.
If your home might become an investment property
This is one of the most consequential - and most overlooked - planning considerations for Australian homeowners. If there's any chance your current owner-occupied home (PPOR) will one day become a rental property, the structure of your loan now will determine the tax deductions available to you then.
The principle is straightforward: when a property converts to an investment, the interest deductible is based on the outstanding loan balance at the time of conversion. This means:
- If you've been making extra repayments via redraw, your loan balance is lower - and your future tax deduction is lower
- If you've been keeping extra cash in an offset account instead, your loan balance is unchanged - and your future tax deduction is maximised
Same household, five years later - different loan structures
| Used redraw | Used offset | |
|---|---|---|
| Original loan | $700,000 | $700,000 |
| Extra savings over 5 years | $80,000 (paid into loan) | $80,000 (sitting in offset) |
| Loan balance at conversion | ~$570,000 | ~$650,000 |
| Deductible interest base (at 6.2%) | ~$35,340/yr | ~$40,300/yr |
| Annual tax deduction difference (37% bracket) | - | ~$1,835 more per year |
The offset structure preserves a higher deductible loan balance at conversion. The $80,000 in savings is in either case - it's just that in the offset scenario, it's accessible cash rather than locked into a lower loan balance.
This is why property investors and financial advisers often say: if there's any chance your home becomes a rental, maximise the loan balance and park savings in an offset - not in the loan via redraw. The tax deductions over a 30-year mortgage can be worth tens of thousands of dollars.
Fees and when an offset might not be worth it
Offset accounts are not free. Loans that include an offset feature typically come packaged with an annual fee - commonly around $350–$400 per year across major lenders. The loan's interest rate may also be slightly higher than a basic variable rate loan without offset.
This means the offset is only worth it if the interest saving exceeds the cost. As a rough guide, at a 6.2% loan rate, each $1,000 in the offset saves approximately $62 in interest per year. To break even on a $395 annual fee, you'd need an average offset balance of around $6,400 throughout the year.
| Average offset balance | Annual interest saving (at 6.2%) | Annual package fee | Net benefit |
|---|---|---|---|
| $5,000 | $310 | $395 | −$85 (net cost) |
| $10,000 | $620 | $395 | +$225 |
| $30,000 | $1,860 | $395 | +$1,465 |
| $60,000 | $3,720 | $395 | +$3,325 |
| $100,000 | $6,200 | $395 | +$5,805 |
Note that some lenders - particularly the digital and non-major lenders - now offer offset accounts on certain variable products with no annual fee, or with the fee waived as part of a promotion. These can represent significantly better value if the loan rate is competitive. For investors, the tax argument for offset (vs redraw) often makes it worthwhile regardless of the fee - but always run the numbers for your specific situation.
Frequently asked questions
Does money in an offset account earn interest?
No - you don't earn interest on the balance. Instead, the balance reduces the interest charged on your loan. The economic benefit is equivalent (or better, once tax is accounted for), but technically no interest is credited to the offset account. This is why the savings are not assessable income.
Can I have an offset on an investment property loan?
Yes, and for the reasons covered in the tax section above, it's generally strongly recommended. The interest deduction on the investment loan remains fully intact regardless of how much you hold in the offset or withdraw from it. This is the key advantage over redraw for investors.
What happens if my offset balance exceeds my loan balance?
Most lenders cap the offset benefit at the loan balance - meaning if you have more in the offset than the outstanding loan, interest is calculated on zero. You won't earn interest on the surplus. Some lenders will treat the two as equal rather than paying out interest on the excess. In this situation, it may be worth making a lump sum repayment to reduce the loan, or discussing refinancing options.
Do all lenders offer offset accounts?
No. Offset accounts are primarily available on variable rate home loans, and not all variable rate products include them. Some lenders only offer redraw. Others include offset at no extra cost; others package it with an annual fee. If an offset is important to your strategy, confirm it explicitly during the loan comparison process - don't assume.
Is it better to put my savings in an offset or make extra repayments?
For owner-occupiers who are certain they'll never convert the property to a rental, the interest saving is identical - money in the offset and money paid into the loan both reduce the interest calculation by the same amount. The difference is access: offset funds are immediately available; extra repayments require a redraw to access, which may have restrictions. For anyone with any possibility of converting to investment, keeping money in offset is strongly preferable for the tax reasons outlined above.
Can a partner or spouse use the same offset account?
Generally yes - most lenders allow joint offset accounts linked to a home loan. The account simply needs to be in the same name(s) as the loan account. For multiple offset accounts, some can be individual and some joint, subject to lender rules. Confirm with your lender as part of the setup process.
Can I use multiple people's salaries to go into the offset?
Yes - any money deposited into the offset account reduces the interest calculation, regardless of whose salary it is. Many couples route both salaries into the offset to maximise the daily balance and minimise interest. As long as the funds flow through the account before being withdrawn for expenses, every dollar earns its keep.
Model the impact in Canwi
Canwi models the impact of your offset balance on your home loan - including how different average balances affect the total interest paid and the life of the loan. You can also compare scenarios where excess cash goes into offset vs extra repayments vs other investments, and see how the numbers stack up over your full financial plan.
General information only. This article provides general information about offset accounts and home loan structures and does not constitute financial product advice or tax advice. Tax treatment depends on individual circumstances and the specific structure of your loan.
