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How to Pay Off Your Mortgage Faster in NZ
Most people with a mortgage just... pay it. The minimum, every month, for 25 or 30 years. It works — eventually — but it's an expensive way to own a home. On a $600,000 mortgage at 5.5% over 25 years, you'll pay $505,357 in interest. That's on top of paying back the $600,000 you borrowed. The bank collects more than half a million dollars for the privilege of lending you money. A few simple changes — none of which require extra income — can cut that figure significantly. Here's what actually works.
Switch to fortnightly payments — but do it properly
There are 26 fortnights in a year, but only 12 months. Pay fortnightly at exactly half your monthly amount, and you'll sneak in one full extra payment every year without noticing.
The maths:
| Monthly: $3,685 × 12 | $44,220/year |
| Fortnightly: $1,842.50 × 26 | $47,905/year |
| Difference | $3,685 — one full extra payment per year |
Based on a $600,000 mortgage at 5.5% over 25 years.
This works whether you're paid fortnightly or monthly. The saving comes from paying more money per year — not from paying more frequently. The frequency is just what makes it happen automatically.
Watch out: when you ask your bank to switch to fortnightly, they may set your payment lower than half your monthly amount. Ask them specifically to set your fortnightly payment to exactly half your current monthly repayment — for example, if you pay $3,685 monthly, ask for $1,842.50 fortnightly.
Pay a little extra, every fortnight
This is the biggest lever most homeowners have — and you don't need much for it to make a real difference.
Extra fortnightly repayments on a $600,000 mortgage at 5.5% over 25 years:
| Extra per fortnight | Interest saved | Time saved |
|---|---|---|
| $100 | $64,247 | 2 yrs 9 mths |
| $200 | $113,097 | 4 yrs 11 mths |
Figures assume extra payments start from day one of the loan.
Interest on your mortgage is calculated on your remaining loan balance. Every extra dollar you pay reduces that balance — which reduces future interest — which reduces the balance faster. The effect builds over time.
Starting the same extra payments 10 years into your mortgage saves significantly less than starting today. Earlier is always better.
Check your loan first. Most fixed-rate mortgages in NZ allow extra payments up to a limit — usually around $500–$1,000 per fortnight — without any fees. Above that, your bank may charge a break fee. Check your loan agreement or give your bank a quick call before increasing your payments.
And be realistic about the amount. A modest extra payment you keep up for years does far more than an ambitious one you abandon in six months.
Apply windfalls to your mortgage
A tax refund. A work bonus. An inheritance. Money from selling a car. When unexpected money arrives, your mortgage is usually the best place for it.
The saving depends on how much you put in and how much time is left on your loan — so there's no single number worth quoting here. What's true in every case: the sooner you do it, the more interest you avoid.
On a fixed rate? Check with your bank before making a large lump sum payment — some loans limit how much extra you can pay without fees. If your fixed term is ending soon, timing a lump sum for then means no restrictions at all.
Don't let a lower rate become a missed opportunity
When your fixed term ends and you refix at a lower rate, your bank will offer you a lower minimum repayment. Most people take it — it feels like breathing room.
But if you keep paying what you were paying before, that extra amount goes straight off your loan balance. Over several years, this adds up significantly — and you won't notice the difference in your day-to-day budget because you were already used to paying the higher amount.
It's one of the easiest wins in personal finance: do nothing different, save thousands.
Not sure when to refix, or whether to break early? If your fixed term is still running but rates have dropped, it might be worth breaking out of it early and locking in a lower rate now — even after paying the break fee. Use Owly's Break Fee Calculator to see if the numbers stack up, or read the When to Refix guide for help timing your decision.
Clear other debts first, then redirect the money
If you have a car loan, personal loan, or credit card debt alongside your mortgage, clear those first — they almost always charge higher interest rates than your mortgage.
When they're gone, don't let that repayment disappear into everyday spending. Redirect it straight to your mortgage instead. You were already living without that money — now it's working for you.
See what's possible with your numbers
These strategies work. How much they work for you depends on your specific loan — your balance, your rate, how long you have left. Owly is a free NZ tool where you can add your mortgage, model different repayment strategies, and see exactly how much time and money you could save. No bank connection required.
Frequently Asked Questions
How much interest will I pay on a $600,000 mortgage in NZ?
On a $600,000 mortgage at 5.5% over 25 years, you'll pay approximately $505,357 in interest — around 84 cents for every dollar you borrowed. Paying even a small amount extra each fortnight can reduce this significantly.
Does switching to fortnightly mortgage payments save money in NZ?
Yes, but the benefit comes from paying more money, not from paying more frequently. If your fortnightly payment is set to exactly half your monthly repayment, you make the equivalent of 13 monthly payments per year instead of 12. That one extra payment per year is what drives the saving. The pure frequency effect on its own saves very little.
How much can I save by paying extra on my mortgage in NZ?
On a $600,000 mortgage at 5.5% over 25 years, paying an extra $100 per fortnight from the start saves $64,247 in interest and cuts 2 years 9 months off your term. Paying an extra $200 per fortnight saves $113,097 and cuts nearly 5 years. The earlier you start, the greater the saving.
Can I make lump sum payments on a fixed rate mortgage in NZ?
Most NZ fixed-rate mortgages allow lump sum payments up to a certain threshold — typically $500 to $1,000 per fortnight — without break fees. Above that limit your bank may charge a fee. Check your loan agreement or contact your bank before making a large lump sum payment.
What should I do when my fixed mortgage rate expires in NZ?
If you refix at a lower rate, keep your repayments at the old amount rather than dropping to the new minimum. The difference goes straight off your loan balance. It is also worth checking whether breaking your current fixed term early and refixing at a lower rate would save more than the break fee costs.