How often you make mortgage repayments affects how quickly you build equity and how much interest you pay over the life of your loan. Switching from monthly to fortnightly payments is one of the simplest ways to shave years off a 30-year mortgage — at no extra monthly cost.
The Three Standard Options
NZ banks offer three standard repayment frequency options:
- Monthly — one payment per month (12 per year)
- Fortnightly — one payment every two weeks (26 per year)
- Weekly — one payment per week (52 per year)
The same repayment amount expressed at different frequencies:
| Monthly | Fortnightly equivalent | Weekly equivalent |
|---|---|---|
| $3,600 | $1,800 | $900 |
Why Fortnightly Saves Money
The maths is simple but often misunderstood.
12 monthly payments of $3,600 = $43,200/year
26 fortnightly payments of $1,800 = $46,800/year
That’s $3,600 more per year — exactly one extra monthly payment — without feeling like you’re paying extra. Because there are 26 fortnights in a year (not 24), fortnightly payments result in 13 “monthly payment equivalents” annually rather than 12.
That one extra payment per year, applied directly to the principal, compounds significantly over a 30-year loan.
Impact on a $600,000 Mortgage at 6.0%
Standard 30-year term, monthly repayments:
- Monthly payment: $3,597
- Total payments: 360
- Total interest: ~$694,920
Switching to fortnightly (half the monthly amount, 26× per year):
- Fortnightly payment: $1,799
- Years saved: approximately 2.5 years
- Interest saved: approximately $52,000
Comparing All Three Frequencies
Using a $600,000 mortgage at 6.0% over 30 years:
| Frequency | Payment | Total per year | Term | Interest paid | Interest saved vs monthly |
|---|---|---|---|---|---|
| Monthly | $3,597 | $43,164 | 30 years | $694,920 | — |
| Fortnightly | $1,799 | $46,774 | 27 years 5 months | $642,800 | ~$52,120 |
| Weekly | $900 | $46,800 | 27 years 2 months | $641,200 | ~$53,720 |
The difference between fortnightly and weekly is small — most of the saving comes from switching away from monthly. Weekly payments save only marginally more than fortnightly.
Important: Confirm the Fortnightly Amount with Your Bank
When setting up fortnightly repayments, confirm the fortnightly amount is exactly half your monthly payment.
Some banks will suggest a fortnightly “equivalent” payment that equates to the same annual total as your monthly payments — i.e., they divide the annual amount by 26, which gives a smaller fortnightly payment. This eliminates the extra payment benefit.
Ask explicitly: “I want to pay exactly half my monthly repayment amount fortnightly, so that I make the equivalent of 13 monthly payments per year.”
Switching Your Payment Frequency
To switch frequency:
- Contact your bank’s mortgage team by phone or via internet banking (not always available online for fixed-rate loans)
- Request the frequency change — specify that you want to switch to fortnightly and confirm the repayment amount
- Set up new automatic payments on your fortnightly cycle
- Cancel any existing monthly direct debit to avoid double-paying
Does payment frequency affect fixed rates? You can switch payment frequency on a fixed-rate loan — this doesn’t break the fixed rate and doesn’t trigger a break fee. Payment frequency is independent of your interest rate structure.
Offset Mortgages and Daily Interest
For revolving credit mortgages (where interest is calculated daily on the outstanding balance), payment frequency works differently. The benefit isn’t primarily from extra payments per year but from reducing the average daily balance as quickly as possible. For revolving credit:
- Depositing your salary as soon as it’s received reduces the average daily balance
- The timing of each deposit matters — earlier in the month = more interest saving
- Withdrawal patterns matter too — minimising the average balance is the goal
See Revolving Credit Mortgage NZ for how daily interest offset mortgages work.
Combine With Other Strategies
Payment frequency works best as part of a broader strategy:
- Increase the payment amount by $100–$500 above the minimum — combined with fortnightly frequency, this significantly accelerates paydown
- Redirect windfalls (tax refunds, bonuses) directly to the floating or revolving credit portion
- Shorten the term when refixing — going from 28 years remaining to 25 years increases repayments but reduces interest substantially
See Pay Off Your Mortgage Faster NZ for the full strategy guide.
Further Reading
- Pay Off Your Mortgage Faster NZ — complete repayment strategy guide
- Lump Sum Mortgage Payments NZ — making extra lump sum payments
- Revolving Credit Mortgage NZ — daily interest reduction strategy
- How Home Loans Work in NZ — understanding amortisation