Market Intelligence · Mortgage & Finance · 6–8 minute read
How to Potentially Save Nearly US$150,000 in Mortgage Interest Without Negotiating a Lower Interest Rate
Most borrowers focus on the interest rate. Few focus on how they repay their mortgage.
When shopping for a home loan, most people compare interest rates.
That’s understandable. Even a small reduction in the interest rate can save thousands of dollars over the life of a mortgage.
But there is another way to significantly reduce the total cost of borrowing without changing your loan product or negotiating a lower rate: changing your repayment strategy.
To illustrate this, let’s compare four investors who all borrow exactly the same amount from the same bank under identical loan conditions.
Loan Assumptions
- Loan Amount: US$500,000
- Interest Rate: 5.00% per annum
- Loan Type: Principal & Interest
- Loan Term: 30 years
- Interest calculated daily (illustrated using a standard amortization model)
- No fees, redraws, offset account or interest rate changes
The only difference between each investor is how and when they choose to repay the loan.
Mortgage Comparison
| Investor | Repayment Strategy | Loan Paid Off | Total Interest Paid | Interest Saved* |
|---|---|---|---|---|
| A | Monthly repayments | 30.0 years | US$466,279 | US$0 |
| B | Fortnightly repayments | ~25.2 years | ~US$378,824 | ~US$87,455 |
| C | Fortnightly repayments + US$50 extra each fortnight | ~23.5 years | ~US$350,313 | ~US$115,966 |
| D | Weekly repayments + US$110 extra each week | 21.54 years | US$316,804 | US$149,475 |
*Compared with Investor A.
Interactive Chart
Outstanding Mortgage Balance Over Time
Illustrative comparison between Investor A (monthly repayments) and Investor D (weekly repayments plus US$110 extra per week).
Key Insight
The bank did not reduce Investor D’s interest rate.
The loan amount remained exactly the same.
The only difference was the repayment strategy.
By making more frequent repayments and consistently paying more than the minimum required, Investor D reduced the outstanding principal faster, resulting in significantly less interest being charged over the life of the loan.
What Changed?
Nothing.
- The loan amount remained US$500,000.
- The interest rate remained 5.00% per annum.
- The lender did not reduce the interest rate.
- The loan product remained exactly the same.
The only thing that changed was the borrower’s repayment behaviour.
Why Does This Work?
Mortgage interest is calculated on the outstanding loan balance.
Every repayment reduces the principal. Once the principal is lower, future interest is calculated on a smaller balance.
Making repayments more frequently reduces the loan balance sooner, while paying more than the minimum repayment accelerates that reduction even further.
Every extra dollar paid towards principal permanently reduces future interest charges.
Over many years, those savings compound.
Looking at Investor A and Investor D
Investor A follows the standard repayment schedule and pays approximately US$466,279 in interest over the life of the mortgage.
Investor D borrows exactly the same amount from the same bank at exactly the same 5.00% interest rate, but chooses a different repayment strategy by making weekly repayments and adding US$110 to every weekly payment.
The result is remarkable.
- The mortgage is repaid in approximately 21.5 years instead of 30 years.
- Total interest falls to approximately US$316,804.
- Total interest saved is approximately US$149,475.
The bank never reduced Investor D’s interest rate.
Investor D simply reduced the amount of time the bank had money outstanding.
Another Way to Look at It
Suppose another borrower wanted to keep the standard 30-year mortgage but pay the same total interest as Investor D.
Using the same loan amount and the same amortization model, that borrower would need an interest rate of approximately 3.58% per annum instead of 5.00% per annum to finish with approximately US$316,804 in total interest.
In other words, although Investor D’s contractual mortgage rate never changed, the lifetime borrowing cost was broadly comparable to borrowing at approximately 3.58% per annum over a traditional 30-year loan.
That’s the power of disciplined repayment behaviour.
Key Takeaways
- Your repayment strategy can have a significant impact on the total cost of your mortgage.
- More frequent repayments reduce the loan balance sooner.
- Consistently paying more than the minimum repayment accelerates principal reduction.
- Every reduction in principal lowers future interest charges.
- Small, regular additional repayments can shorten a mortgage by many years and potentially save well into six figures in interest over the life of a large home loan.
Conclusion
Most borrowers spend weeks searching for a lower interest rate.
Far fewer spend time designing a better repayment strategy.
Yet, as this example demonstrates, how you repay your mortgage can be almost as important as the interest rate itself.
While negotiating a lower rate is always beneficial, consistently making more frequent repayments and adding manageable extra amounts can substantially reduce both the life of your mortgage and the total interest you pay.
Sometimes, the smartest way to lower the cost of borrowing isn’t asking the bank for a better deal.
It’s making your money work harder every week.
Disclaimer: This example is for educational purposes only and is based on the assumptions listed above using a standard loan amortization model. Actual mortgage outcomes will vary depending on your lender’s repayment processing, interest calculation method, day-count convention, rounding policy, fees, loan features and future interest rate changes.