An offset account is arguably the most powerful tool for reducing your mortgage interest. Here's how it works — and why the bank won't always tell you about it.

The Product Banks Won't Always Recommend

An offset account is a transaction account attached to your home loan. The bank doesn't pay you interest on the money sitting in it. Instead, every day when the bank calculates your daily interest, they subtract the offset balance from your loan balance first.

If your home loan balance is $500,000 and you have $5,000 in your offset account, the bank calculates interest on $495,000 instead of $500,000. That's it. Simple maths, powerful results.

Why This Beats a Savings Account

Imagine you have a spare $10,000. You could park it in a high-interest savings account earning 4%, or use it to offset your 6% home loan.

In the savings account, you'd earn about $33 per month. But then you pay tax on that interest — roughly 30% for most earners. Your real return? About $23.

With the offset, you save $50 per month in home loan interest ($10,000 × 6% ÷ 12). And you don't pay tax on interest you save. The offset gives you a better after-tax return, every time.

It Works Like Your Normal Account

An offset account is exactly like your day-to-day transaction account. Your income gets paid into it. You have a debit card. You can tap-and-go at the shops, pay bills with BPAY, and withdraw cash from any ATM.

The only difference is that while your money sits there — even for a few days between pay cycles — it's actively reducing the interest on your home loan.

Offset vs Redraw

Mathematically, money in an offset account and money in redraw have the same effect on your interest calculation. But there's a critical tax difference.

If your property might become a rental in the future, an offset account protects your tax position. Money in redraw is treated as a permanent reduction of the loan principal. If you later redraw those funds for personal use, the ATO won't let you claim the interest as a tax deduction. With an offset, the loan balance never actually changes — you haven't reduced the principal, so your full loan amount remains deductible when the property becomes an investment.

Multiple Offset Accounts

Many people keep separate accounts for different purposes — bills, holidays, emergency fund. If these are regular savings accounts earning no interest, that money is doing nothing for you.

Some lenders offer multiple offset accounts. All of them offset against the one home loan. You keep your budgeting categories, and every dollar across all those accounts is reducing your daily interest calculation.

Is It Worth the Extra Cost?

Offset accounts typically come as part of a "professional package" with an annual fee of $150–$400. The question to ask: will I keep an average balance high enough to save more than the fee?

On a 6% loan with a $395 annual fee, you'd need roughly $6,600 in your offset at all times to break even. Most working Australians with a salary flowing through the account will comfortably exceed this.