Making extra repayments on your NZ mortgage is one of the safest, highest-return financial moves available — every extra dollar you pay reduces your interest bill dollar-for-dollar, at your mortgage rate. Use the calculator below to see exactly how much time and money you save.
On a $700,000 mortgage at 5.50% over 30 years, paying an extra $200/fortnight saves approximately $97,000 in interest and cuts 4 years off your loan. A $20,000 lump sum saves around $52,000 and shaves 2.5 years off the term.
Extra Repayment Calculator
Extra Repayment Calculator
Extra Repayments
Why Extra Repayments Save So Much
Every dollar you pay beyond the minimum repayment goes directly to reducing the loan principal — the amount you owe. A smaller principal means less interest charged in every subsequent period, which accelerates the payoff and compounds over time.
This is mathematically equivalent to earning your mortgage rate as a guaranteed, risk-free return. If your mortgage rate is 5.50%, paying it down is the same as investing at 5.50% guaranteed — better than most term deposits, without tax.
Impact of Extra Repayments — Quick Reference
Based on $700,000 mortgage, 5.50% rate, 30-year term. Fortnightly frequency.
| Extra per fortnight | Interest saved | Time saved | New payoff |
|---|---|---|---|
| $100 | ~$52,000 | ~2.2 years | 2052 |
| $200 | ~$97,000 | ~4.1 years | 2050 |
| $500 | ~$196,000 | ~8.5 years | 2046 |
| $1,000 | ~$291,000 | ~12.5 years | 2042 |
Impact of Lump Sum Payments
Based on $700,000 mortgage, 5.50%, 30 years, applied in year 1.
| Lump sum | Interest saved | Time saved |
|---|---|---|
| $5,000 | ~$13,500 | ~7 months |
| $10,000 | ~$26,000 | ~14 months |
| $20,000 | ~$49,000 | ~2.5 years |
| $50,000 | ~$108,000 | ~5.5 years |
When Can You Make Extra Repayments?
Fixed rate mortgages
Most NZ banks allow up to $500–$1,000 per year in extra repayments on a fixed rate mortgage before a break fee applies. Some banks have higher thresholds — ASB and BNZ typically allow more. Check your loan agreement before making a large lump sum payment while on a fixed rate.
If you want unlimited overpayments, wait until rollover (when your fixed term expires) or move that portion of the loan to floating.
Floating rate mortgages
No restrictions — you can make extra repayments of any size, at any time, with no fee. This is the main advantage of floating over fixed for borrowers with irregular cash flows (bonuses, commissions, freelance income).
Revolving credit / offset accounts
Extra cash sitting in a revolving credit facility or offset account reduces the daily interest charged, achieving the same effect as direct overpayment — but with full liquidity. See the revolving credit mortgage guide.
Strategies for Making Extra Repayments
Round up your repayments
If your minimum fortnightly repayment is $1,847, round up to $2,000. The extra $153/fortnight is barely noticeable in your budget but saves years over a 30-year term.
Pay fortnightly instead of monthly
Switching from monthly to true fortnightly payments (not just half-monthly) results in 26 payments per year instead of 24 (2 months × 12 months). This effectively makes one extra monthly payment per year — saving roughly 3–4 years on a standard mortgage.
Apply windfalls immediately
Tax refunds, annual bonuses, inheritance, KiwiSaver employer contributions (if you’ve exited KiwiSaver) — any unexpected lump sum is best applied to the mortgage if you’re on floating or approaching rollover.
Set a regular automatic extra payment
Set up a second automatic payment from your salary account directly to your mortgage. Even $100/fortnight extra on a $500,000 loan saves over $40,000 in interest over the loan term.
Frequently Asked Questions
How much does an extra $200 per fortnight save on a mortgage NZ?
On a $700,000 mortgage at 5.50% over 30 years, an extra $200/fortnight saves approximately $97,000 in interest and reduces the loan term by about 4 years. The exact figure depends on your balance and rate.
Are there limits on extra mortgage repayments in NZ?
Yes, on fixed rate mortgages. Most NZ banks allow $500–$1,000 per year in extra repayments without a break fee. Floating rate and revolving credit mortgages have no restrictions.
Is it better to invest extra money or pay off the mortgage?
If your mortgage rate is above the after-tax return on your investment, paying the mortgage wins mathematically. At 5.50%, you’d need consistent after-tax investment returns above 5.50% to favour investing. See the full analysis in pay off mortgage or invest NZ.
Can I make a lump sum payment on my NZ mortgage?
Yes, but check your fixed rate contract first. Most lenders allow up to $1,000/year extra on fixed rate mortgages. For larger lump sums, wait until rollover or put the funds in an offset/revolving credit account in the meantime.
Does the extra repayment reduce the term or reduce repayments?
With most NZ table loans, the repayment amount stays fixed — extra payments reduce the term. Some lenders allow you to choose; check with your bank.
Related Guides
- How to Pay Off Your Mortgage Faster NZ — full strategies guide
- Lump Sum Mortgage Payments NZ — maximising windfall payments
- Weekly vs Fortnightly vs Monthly Payments NZ — switching frequency explained
- Revolving Credit Mortgage NZ — offset repayment alternative
- Mortgage Repayment Calculator NZ