Model house on a house plan with a magnifying glass, representing checking your mortgage offset account
Photo by Tierra Mallorca on Unsplash

Mortgage Offset Calculator: Check Exactly What Interest You Should Be Paying

Enter your loan balance, offset balance and interest rate, and this free calculator works out exactly what interest you should be charged on your mortgage offset account, with every step of the maths shown. It's worth checking: a 2026 ASIC review found banks paid out more than $55 million after failing to correctly set up or link customers' offset accounts, and warned that more hidden errors are likely still out there.

Your loan details

$
$
% p.a.
Use 28–31 depending on the month you're checking.

Result

Net balance
$0
Daily rate
0%
Daily interest charge
$0
Interest for the month
$0

Working out

Want to understand the maths behind this, or what to do if the numbers don't match your bank statement? Read the offset account FAQ, or browse the guides on offset accounts, refinancing, and getting the most out of your home loan.

This is an estimate for illustrative purposes only, based on the average of your loan and offset balances for the month. It does not account for daily balance fluctuations, principal repayments during the month, fees, or mid-month rate changes. If your figures don't match what your bank has charged you, contact your lender with your workings. If unresolved, you can escalate a complaint to the Australian Financial Complaints Authority (AFCA). Not financial advice.