Is money in my offset account actually paying off my mortgage?
The most common offset question in Australia - and the confusion is understandable, because the answer is "no, but it acts like yes."
Short answer: no - your loan balance doesn't change, and that's the feature, not a flaw. Money in an offset account is never paid into the loan. It stays yours, fully accessible, in what works like an everyday transaction account. What changes is the interest calculation: per MoneySmart, most lenders subtract your offset balance from your loan balance every day before calculating that day's interest.
So why does it feel like paying the loan off?
Because of what happens to your repayment. Your minimum repayment stays exactly the same - but with less interest being charged, more of each repayment lands on the actual loan balance instead of interest. Over the years, the balance falls faster, and the loan can finish years early. MoneySmart's own example: with a $500,000 loan and $20,000 sitting in offset, interest is only charged on $480,000. The effect on total interest looks a lot like an extra repayment - the difference is your $20,000 never got locked away.
The distinction that actually matters
Extra repayment: money goes into the loan. Balance drops. Getting it back means a redraw facility (with possible limits, delays, or fees) or refinancing.
Offset: money sits beside the loan. Balance unchanged. You can spend it tomorrow - and every day it sits there, it's cutting the interest calculation.
Neither is free money: some lenders charge for offset features through package fees or slightly higher rates, and MoneySmart notes that a consistently small balance (roughly under $10,000) may not justify those costs. The honest question isn't "is offset good" but "does my balance, held for this long, beat the fee."
The calculator runs the month-by-month arithmetic with your loan, rate, offset balance, and monthly offset additions together - so you can see the years and dollars difference rather than taking anyone's word for it. It also includes a reconciliation checker: enter what your bank statement actually shows and it tells you whether the interest charge matches the daily-balance math, or whether it is worth a call to your lender to ask why.
General information only. This page explains how a loan feature works mathematically - it isn't financial advice, doesn't consider your circumstances, and loan products differ. For guidance on your situation, consider a licensed adviser; for impartial basics, Australia's government-run MoneySmart is a good starting point.