Because mortgage interest is generally calculated on your outstanding balance, any extra amount you pay reduces that balance immediately, which reduces the interest charged going forward. Even modest, regular extra repayments can add up to meaningful savings over the life of a loan.
Why Extra Repayments Are So Effective
As explained in how mortgage repayments are calculated, interest is charged on your current loan balance. Every extra dollar you pay reduces that balance, which means less interest accrues on it from that point forward. Because this compounds over the remaining life of the loan, extra repayments made earlier tend to have a bigger impact than the same amount paid later.
A Simple Illustration
Take a $500,000 loan at 6% interest over 30 years. Adding a modest extra repayment of $200 a month on top of the standard repayment can reduce the total interest paid over the life of the loan by a substantial amount, and can also shorten the loan term by several years. The exact figures depend on your loan size, rate and term, but the underlying pattern — smaller balance, less interest, shorter loan — holds consistently.
You can test this directly using the Smarter Mortgage Calculator, which lets you add an extra repayment amount and instantly see the estimated interest saved and time shaved off your loan.
Ways Extra Repayments Are Typically Made
- A fixed additional amount added to each regular repayment
- Occasional lump sums, such as a tax return or bonus
- Rounding up repayments to a convenient whole number
- Directing spare income into an offset account, which reduces interest in a similar way
Things Worth Checking First
Some loans, particularly fixed-rate loans, place limits on how much extra you can repay each year without incurring a fee. It's worth checking your loan's terms before committing to a regular extra repayment plan, and confirming whether the facility allows you to redraw those funds later if your circumstances change.
Balancing Extra Repayments With Other Priorities
Putting spare money toward your mortgage isn't always the only option worth considering — some people also weigh it up against building an emergency fund, paying down higher-interest debts first, or other financial goals. There's no single right approach; it depends on your overall financial picture and priorities.
- Extra repayments reduce your loan balance immediately, cutting future interest.
- Extra repayments made earlier in the loan tend to save more interest overall.
- Check your loan's terms for any limits or fees on extra repayments, especially on fixed rates.
- Weigh extra repayments against other financial priorities like an emergency fund.
See exactly how much you could save with the Smarter Mortgage Calculator's extra repayment feature.
This article provides general information only and does not constitute financial, credit, legal or tax advice. Lending criteria, fees and loan conditions vary. Consider speaking with a lender, mortgage broker or appropriately qualified professional before making financial decisions.