Offset Account Explained: How It Works and What It Actually Saves You

An offset account is a everyday transaction account linked to your home loan. Every dollar sitting in it is subtracted from your loan balance before the bank calculates interest for the day — you don't earn interest on the savings, but you avoid paying interest on that same amount at your (much higher) mortgage rate. It's one of the few home loan features that costs a small annual fee but can save tens of thousands of dollars over the life of a loan, which is why most package home loans in Australia are built around one.

The 30-second summary

• Interest is calculated daily on loan balance minus offset balance, not on the full loan balance.
• A 100% offset means every dollar in the account offsets a dollar of the loan. Some older loans only offer partial (e.g. 40%) offset.
• On a $500,000 loan at 6.00% p.a., keeping a constant $50,000 in offset saves ≈$194,600 in interest and pays the loan off ~5.3 years early, if you keep making the original repayment.
• Offset money stays fully accessible — unlike redraw, it's still sitting in your everyday account, not paid into the loan.
• For investment properties, offset preserves interest deductibility in a way that redrawing can jeopardise.
• Offset accounts typically come with an annual package fee (~$300–$400) — it pays for itself once your average balance clears a few thousand dollars.

How the interest calculation actually works

Most Australian home loans charge interest daily on the outstanding balance, then debit it monthly. An offset account doesn't touch your loan balance on paper — it sits alongside it, and each day the bank nets it off before running the interest calculation:

Daily interest charged = (Loan balance − Offset balance) × (Interest rate ÷ 365)

If you have a $500,000 loan and $50,000 sitting in a linked 100% offset account, you pay interest as if the loan were $450,000 — while the $50,000 remains entirely yours, spendable the same afternoon if you need it.

A worked example — $500,000 loan at 6.00% p.a.

Take a $500,000 loan, 30-year term, 6.00% p.a., principal & interest, with the borrower continuing to pay the original scheduled repayment ($2,998/month) even after their balance falls faster than expected. This is exactly what the offset calculator models under the hood:

Scenario	Interest paid over the loan	Time to pay off	Interest saved	Time saved
No offset	$579,191	30.0 years	—	—
$30,000 constant offset	$450,873	26.5 years	$128,318	3.5 years
$50,000 constant offset	$384,585	24.7 years	$194,606	5.3 years

Two things stand out. First, the saving isn't linear with the offset balance — a bigger buffer disproportionately shortens the loan because every dollar saved on interest is a dollar that goes straight to principal instead, which then saves interest the following month too. Second, these figures assume the offset balance stays constant for the life of the loan — in practice most people's balances fluctuate with pay cycles and bills, so the average balance over the year is what actually matters, not the balance on any single day.

Full (100%) offset vs partial offset

Not all "offset" products are equal:

• 100% offset — every dollar in the account reduces the interest-bearing loan balance dollar-for-dollar. This is the standard on most Australian package home loans (the ones with an annual fee bundling offset, a credit card, and rate discounts).
• Partial offset (commonly 40%) — only a portion of your balance counts. A $50,000 balance in a 40%-offset account only offsets $20,000 of the loan. These typically appear on older or "basic" no-fee loan products.

Always check your loan's product disclosure statement for the exact offset percentage — "offset" in a product name doesn't guarantee 100%.

Offset vs redraw — the difference that actually matters

This is the most common point of confusion, and the honest answer is: for the interest calculation alone, a dollar in full offset and a dollar in redraw save you the same amount. Both reduce the balance interest is charged on. The real differences sit elsewhere:

	Offset account	Redraw facility
Where the money sits	Separate transaction account, linked to the loan	Paid directly into the loan itself
Accessibility	Instant — debit card, transfers, ATM	Often slower; some lenders cap redraws, charge a fee, or require online requests
Effect on the loan	Loan balance is unchanged on paper	Loan balance is reduced
Investment property tax treatment	Interest stays 100% deductible — the loan itself is never touched	Redrawing and re-borrowing can taint the loan's purpose, risking partial loss of deductibility
Availability on fixed rates	Rare, sometimes capped	More commonly available

For an owner-occupier who won't touch the money, the two are close to interchangeable. For an investor, or anyone who might want the funds back, offset is almost always the safer structure.

What an offset account costs

Offset facilities are usually bundled into a "package" home loan with an annual fee, typically $300–$400 per year, which often also includes a discounted interest rate and a fee-free credit card. Do the maths on your own numbers: at 6.00% p.a., you need roughly $6,700 average balance sitting in the account to earn back a $400 annual fee in interest saved. Most people clear that easily with a normal transaction balance plus even a modest emergency fund — which is why offset is worth it for most borrowers, but worth checking if you genuinely keep very little cash on hand.

Frequently asked questions

Is an offset account worth the annual fee?

Usually yes once your balance clears roughly one to two times the annual package fee at your interest rate. At 6.00% p.a., a $400/year fee is covered by keeping about $6,700 permanently in the account. It stops being worth it only if you'd otherwise keep almost nothing there.

Offset account or redraw facility — what's the difference?

The interest saving is the same per dollar. The differences are practical: offset funds are instantly spendable from a normal account, while redraw has technically gone into the loan and can be slower, fee-charged, or restricted to access. For investment loans, offset also protects interest deductibility in a way redrawing can put at risk.

Can I get an offset account on a fixed-rate home loan?

Rarely, and usually capped if available at all. Most 100% offset facilities are attached to variable-rate loans. If you're considering fixing and offset matters to you, ask the lender exactly what survives the fixed period before you commit.

Do I need a 100% offset, or is partial offset still worth it?

100% offset (standard on most package loans) offsets your full balance. Partial offset — commonly 40% — still saves money, just proportionally less. Check the product disclosure statement, since not every loan marketed with "offset" in the name offsets the full 100%.

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Run your own numbers — loan size, offset balance, and rate — in the offset calculator, or see how a growing offset balance compares to making extra repayments instead. For every other stage of buying and owning a home, see the full guide to Australian mortgage calculators.

This article provides general information current at July 2026 and does not constitute personal financial advice. Offset facility terms, fees, and availability vary by lender and loan product — confirm the specifics with your lender or broker before making a decision.