Every additional dollar you pay on your home loan reduces the principal balance — which means less interest is charged the next day, the next month, and every month thereafter. The compounding effect of regular extra repayments is remarkably powerful: on a $500,000 loan at 6.5% over 30 years, an extra $200 per month saves approximately $110,000 in total interest and cuts 6.5 years off the loan term. This guide explains the mathematics and helps you find the strategy that works for your situation.
The Mathematics: How Extra Repayments Save You Money
Home loan interest in Australia is calculated daily on the outstanding balance. Each day, the lender calculates: (outstanding balance × annual rate) ÷ 365. Any additional payment you make immediately reduces the outstanding balance — which reduces the daily interest charge from that point forward.
The earlier in the loan term you make extra repayments, the greater the impact. This is because the compounding effect has more time to work. $10,000 in extra repayments in year one of a 30-year loan saves significantly more than $10,000 in extra repayments in year 20.
Here are the savings for a $600,000 loan at 6.5% over 30 years (standard monthly repayments of $3,793):
Extra $100/month: saves $57,000 in interest, reduces term by 3 years 2 months. Extra $200/month: saves $100,000 in interest, reduces term by 5 years 8 months. Extra $500/month: saves $190,000 in interest, reduces term by 10 years 3 months. Extra $1,000/month: saves $281,000 in interest, reduces term by 14 years 5 months. One-off $20,000 lump sum in year one: saves $62,000 in interest, reduces term by 1 year 8 months.
These savings are cumulative — combining regular extra payments with occasional lump sums (tax refund, bonus, inheritance) maximises the effect.
Check for Extra Repayment Limits on Fixed Rate Loans
Most variable rate home loans allow unlimited extra repayments. However, fixed rate loans typically cap extra repayments at $10,000–$30,000 per year during the fixed period. Exceeding this cap may trigger break costs. Always check your loan terms before making large additional payments on a fixed rate loan.
| Extra Repayment | Interest Saved | Term Reduction | Total Saved Over Loan Life |
|---|---|---|---|
| $100/month | $57,000 | 3 years 2 months | $57,000 |
| $200/month | $100,000 | 5 years 8 months | $100,000 |
| $500/month | $190,000 | 10 years 3 months | $190,000 |
| $1,000/month | $281,000 | 14 years 5 months | $281,000 |
| $20,000 lump sum (year 1) | $62,000 | 1 year 8 months | $62,000 |
Fortnightly vs Monthly Repayments: The Simple Switch That Saves Thousands
Switching from monthly to fortnightly repayments is one of the simplest ways to pay off your loan faster — without spending more per pay cycle. Here is how it works:
Monthly: 12 repayments per year. If your monthly repayment is $3,793, you pay $45,516 per year.
Fortnightly: Divide your monthly repayment by two and pay that amount every two weeks. $3,793 ÷ 2 = $1,897 every fortnight. There are 26 fortnights in a year, so you pay $1,897 × 26 = $49,322 per year — that is $3,806 more than the monthly schedule.
This extra payment (equivalent to one additional monthly repayment per year) happens naturally because there are 26 fortnights but only 12 months. On a $600,000 loan at 6.5%, switching to fortnightly repayments saves approximately $85,000 in interest and reduces the loan term by approximately 4.5 years.
Note: Ensure your lender calculates interest on a true fortnightly basis — some lenders collect fortnightly payments but only credit them to your loan monthly, which reduces the benefit. A true fortnightly calculation means each payment reduces the balance immediately and reduces daily interest from that point.
Weekly Payments Save Even More
The same principle applies to weekly repayments. Divide your monthly payment by four: $3,793 ÷ 4 = $948 per week. With 52 weeks per year, you pay $49,296 — slightly more than twelve monthly payments. Weekly payments reduce interest even faster because the balance is reduced more frequently. Savings are approximately 5–10% greater than fortnightly.
Extra Repayments vs Offset Account: Which Is Better?
Both strategies reduce the interest you pay — but they work differently and offer different levels of flexibility.
Extra repayments: Money is paid directly into the loan, reducing the principal. To access these funds later, you need a redraw facility (most variable loans have one, most fixed loans do not). Redrawing may have fees, minimum amounts, and some lenders can restrict or close the redraw facility at their discretion.
Offset account: Money sits in a linked transaction account. The balance offsets the loan principal for interest calculation purposes — but you retain full, unrestricted access to the funds at any time. There are no redraw restrictions because the money never leaves your account.
The interest saving is identical: $50,000 in extra repayments saves the same interest as $50,000 in an offset account (assuming a 100% offset). The difference is flexibility and control.
For most borrowers, the offset account is the better option if your loan product includes one — you get the same interest saving with full liquidity. Extra repayments (with redraw) are suitable if your loan does not include an offset, or if you want the psychological discipline of 'locking away' the funds.
One important distinction for investors: extra repayments on an investment loan that are later redrawn may have different tax implications than offset account funds. Seek accounting advice before redrawing from an investment loan.
- ✓Extra repayments — reduce principal directly, access via redraw
- ✓Offset account — funds offset principal but remain fully accessible
- ✓Interest saving is identical for the same dollar amount
- ✓Offset provides superior flexibility and liquidity
- ✓Redraw on investment loans may have adverse tax implications
- ✓Some fixed rate loans do not allow extra repayments or redraw
- ✓Offset accounts typically require a loan product with this feature (may have higher fees)
Frequently Asked Questions
About the Author
Sakib Manzoor
Senior Finance Wellness Expert
Sakib Manzoor is the founder of Secure Finance and brings extensive experience in Australian mortgage broking and financial wellness. Specialising in helping clients achieve their property finance goals through personalised strategies and expert guidance, Sakib is FBAA accredited and committed to providing clear, actionable advice. All content is written to meet Australian regulatory standards and is regularly updated to reflect current market conditions.