A mortgage might be the largest contract you ever sign — yet the mechanics behind it are rarely explained clearly. Most people know they’ll pay interest, but few understand how repayments are structured, why so much interest is paid in the early years, or how changing from a 25-year to a 30-year term affects the total cost.
This guide explains how NZ home loans actually work, from first drawdown to final repayment.
What Is a Mortgage?
A mortgage is a loan secured against a property. The lender (usually a bank, sometimes a non-bank lender) provides the money to buy the home, and you repay it over an agreed term, often 25 to 30 years in New Zealand, with interest charged on the outstanding balance.
Because the loan is secured, the lender can sell the property to recover what is owed if the loan isn’t repaid. That security is why home loans carry lower interest rates than unsecured borrowing such as personal loans or credit cards.
Key mortgage terms
| Term | What it means |
|---|---|
| Principal | The amount you borrowed |
| Interest | The cost of borrowing, expressed as a % per year |
| Loan term | How long you have to repay, often 25 to 30 years |
| LVR | Loan-to-value ratio: your loan as a % of the property value |
| Repayment | The combined principal and interest you pay each period |
| Equity | The share of the property you own outright (value minus debt) |
How much you can borrow, what deposit you need and how to apply each have their own guides: how much can I borrow, how much deposit do I need, getting a mortgage in NZ and using a mortgage broker.
The Basic Structure: What You’re Actually Agreeing To
When a bank approves your mortgage, you are agreeing to:
- Repay the principal — the amount you borrowed
- Pay interest on the outstanding balance, calculated at the agreed rate
- Secure the loan against the property (the bank has a registered mortgage over the title)
If you fail to make repayments and cannot resolve the situation with the lender, the bank can appoint a mortgagee and sell the property to recover what is owed. This is called mortgagee sale, and is the legal foundation that allows banks to offer large loans at relatively low rates.
How Repayments Are Calculated: Table Loans
The vast majority of New Zealand home loans are table loans (also called principal-and-interest loans). The defining feature is that every repayment is the same dollar amount — but the split between interest and principal changes over time.
How it works
- Interest is calculated on the outstanding loan balance
- As you repay principal, the balance falls — so the interest component of each repayment falls too
- Because the total repayment is fixed, the principal component increases as interest falls
- Over time, more and more of each repayment chips away at the debt
This structure is called amortisation.
Example: $700,000 loan at 6.00% over 30 years
| Year | Annual interest paid | Annual principal paid | Remaining balance |
|---|---|---|---|
| 1 | $41,570 | $8,762 | $691,238 |
| 5 | $39,500 | $10,832 | $657,424 |
| 10 | $36,530 | $13,802 | $609,720 |
| 15 | $32,310 | $18,022 | $543,988 |
| 20 | $26,300 | $24,032 | $453,104 |
| 25 | $17,610 | $32,722 | $325,692 |
| 30 | $5,200 | $45,132 | $0 |
Monthly repayment: ~$4,199. Total interest paid over 30 years: ~$811,640.
The first few years are dominated by interest. This is why making extra repayments early in a mortgage has a disproportionate impact — every extra dollar paid reduces the principal on which future interest is calculated.
Interest Rate Types: Fixed, Floating, and Revolving
Fixed rate
The interest rate is locked in for a set term — typically 6 months, 1, 2, 3, or 5 years. Repayments don’t change during the fixed period.
What happens at the end of a fixed term? When the fixed term expires, the loan “rolls over.” If you don’t act, the bank will automatically move you to its standard floating rate or a default fixed term — which is rarely competitive. This rollover moment is your chance to negotiate a better rate, change your term, or refinance.
Break fees: If you need to exit a fixed rate mortgage before the term ends (because you’re selling, refinancing, or making a large lump-sum repayment), the bank may charge a break fee. This compensates the bank for the loss of the fixed-rate income stream. Break fees can range from nothing to tens of thousands of dollars depending on how rates have moved and how much time remains.
Floating (variable) rate
The interest rate moves up or down with market conditions — mainly driven by the RBNZ’s Official Cash Rate (OCR). Floating rates are usually higher than short-term fixed rates, but they offer:
- No break fees for lump-sum repayments
- Flexibility to switch to fixed at any time
- Repayments that drop automatically when the OCR falls
Revolving credit
A revolving credit mortgage works like a large overdraft. Instead of a fixed repayment schedule, you deposit your salary into the facility and withdraw money as needed. Interest is calculated daily on the outstanding balance, so every day your salary sits in the account, it reduces the amount of interest you’re paying.
Used correctly, a revolving credit facility can cut years off a mortgage without increasing repayments. Used carelessly, it can result in the principal never reducing at all — a real risk for people who treat it like a spending account.
Interest-only loans
An interest-only loan requires only interest payments — the principal doesn’t reduce. These are most common for property investors who want to maximise cash flow and tax deductions. Interest-only terms are typically limited to 5 years for owner-occupiers and require strong justification.
Note: interest deductibility for investors was being phased back in during 2024–2025. Check the current IRD rules before structuring a loan interest-only for investment purposes.
For a detailed comparison of your main options, see our guide on fixed vs floating mortgages in NZ.
Loan Term: 25 Years vs 30 Years
The term of your mortgage determines how long you have to repay it and, significantly, how large your regular repayments are.
| Term | Monthly repayment ($700k at 6%) | Total interest paid |
|---|---|---|
| 20 years | $5,014 | $503,360 |
| 25 years | $4,494 | $648,200 |
| 30 years | $4,199 | $811,640 |
A longer term means lower repayments — but dramatically more interest over the life of the loan. Going from 25 to 30 years on a $700,000 loan costs an extra $163,440 in interest.
The practical approach: Many NZ borrowers take a 30-year loan term (for lower required repayments) but pay as though it’s a 25-year loan. This maintains flexibility — if money is tight one month, you only have to make the minimum repayment — while still reducing the term and interest cost substantially when extra repayments are made consistently.
LVR: The Loan-to-Value Ratio
Your loan-to-value ratio (LVR) is the loan amount as a percentage of the property’s value.
Formula: LVR = (Loan Amount ÷ Property Value) × 100
Example: $560,000 loan on a $700,000 property = 80% LVR
The Reserve Bank (RBNZ) limits how much of each bank’s new lending can go to low-deposit borrowers. Since 1 December 2025, up to 25% of each bank's new owner-occupier lending can go to borrowers with less than a 20% deposit, and up to 10% of new investor lending to investors with less than a 30% deposit. These are caps on a bank’s share of lending, not a ban on any one loan, so most borrowers need a 20% deposit for a home they will live in. Eligible first home buyers can borrow with a 5% deposit through the First Home Loan. For a detailed breakdown, see our LVR restrictions guide.
How Mortgage Drawdown Works
Drawdown is the moment the bank releases the mortgage funds. For a standard residential purchase:
- You exchange contracts with the vendor and your solicitor confirms the details
- On settlement day, your solicitor requests the funds from the bank
- The bank releases the mortgage funds to the vendor’s solicitor
- Ownership transfers to you via the Land Information New Zealand (LINZ) register
- Your mortgage repayments begin (usually from the following month)
For new builds, drawdown often happens in stages aligned with construction milestones — a “progress payment” structure. Each stage draws down a portion of the approved loan.
What Happens When Interest Rates Change?
If you’re on a fixed rate
Nothing happens during the fixed term. Your repayments stay exactly the same regardless of OCR movements. When the term expires, the rate will be set at whatever the market rate is at rollover.
If you’re on a floating rate
Your repayments adjust (usually within a few weeks) when the bank changes its floating rate — typically in response to an OCR decision. A 0.25% OCR cut on a $500,000 floating loan reduces annual interest by approximately $1,250 — or about $104/month.
Rate risk in practice
New Zealand mortgage borrowers faced a sharp lesson in rate risk in 2022–2023, when the OCR rose from 0.25% to 5.50% in 18 months. Many borrowers who had fixed at historic lows rolled off their terms onto rates two to three times higher, significantly increasing repayments.
This is why loan structure and staggering fixed terms matters: if you have a $700,000 loan, splitting it into a $350,000 1-year fix and a $350,000 2-year fix means you’re never fully exposed to a rate change at once.
Principal Repayment vs Interest-Only: What’s the Difference?
| Feature | Principal and interest | Interest-only |
|---|---|---|
| Repayment amount | Higher | Lower |
| Debt reduction | Yes — every repayment reduces the principal | No — principal stays flat |
| Total cost | Lower over the life of the loan | Higher — you’re never reducing the balance |
| Common use | Owner-occupiers, long-term wealth building | Property investors, short-term cash flow |
| Maximum term | Typically 25–30 years | Usually 5 years, then must convert |
Most New Zealand owner-occupiers repay principal and interest. Interest-only periods are usually limited to a set number of years, after which the loan converts to principal and interest.
Redraw and Extra Repayments
Many NZ mortgages allow extra repayments, and some allow you to redraw those extra payments if needed.
- Floating and revolving credit facilities almost always permit extra repayments without restriction
- Fixed rate loans typically allow limited extra repayments without break fees — often up to 5% of the original loan amount per year
- Redraw allows you to withdraw extra repayments you’ve made if circumstances change — though some fixed-rate products don’t permit this
Making extra repayments is one of the most effective ways to cut the cost of your mortgage. Even $200/month extra on a $600,000 loan at 6% over 25 years saves approximately $57,000 in interest and reduces the term by 3.5 years.
Mortgage Insurance and LMI
New Zealand does not have a compulsory Lenders Mortgage Insurance (LMI) system equivalent to Australia. However:
- Some non-bank lenders may charge a low-equity premium or fee for high-LVR lending
- The Kāinga Ora First Home Loan scheme involves a government guarantee to the bank, enabling the lender to approve low-deposit applications — borrowers don’t pay a separate LMI premium
For first home buyers using the First Home Loan, this government underwriting removes the main cost barrier associated with high-LVR lending in other markets. For more detail, see our First Home Loan guide.
How Multiple Loans on One Property Work
Many New Zealand borrowers have more than one “split” on their home loan — for example:
- Loan 1: $400,000 fixed for 2 years at 5.79%
- Loan 2: $200,000 fixed for 1 year at 5.59%
- Loan 3: $100,000 floating (for extra repayments/redraw flexibility)
All three splits are secured against the same property. This structure allows borrowers to:
- Stagger rollover dates (not all fixed terms expire at once)
- Make extra repayments into the floating portion without break fees
- Benefit from different rate terms on different portions
Cross-collateralisation is a related (but riskier) structure where the same loan is secured against multiple properties. This is common for property investors but can create problems when selling one property — the bank holds security over everything.
Mortgage Jargon Decoded
| Term | Plain English |
|---|---|
| OCR | Official Cash Rate: the RBNZ’s benchmark interest rate |
| Break fee | A charge for leaving a fixed-rate mortgage before the term ends |
| Conditional approval | Pre-approval subject to valuation and final checks |
| Caveat | A legal claim registered against a property’s title |
| Conveyancing | The legal process of transferring property ownership (legal fees) |
| Settlement | The date funds transfer and ownership changes |
| Valuation | An independent assessment of the property’s market value |
| Cross-collateralisation | Using one property as security for more than one loan |
| Interest-only | Repayments cover only interest, so the principal doesn’t reduce |
The mortgage glossary defines more terms.
Frequently Asked Questions
What is amortisation? Amortisation is the process of paying off a loan over time through regular repayments. In a fully amortising mortgage, the loan balance reduces to zero by the end of the term. Each repayment covers both interest and principal, with the proportion shifting over time.
Is the interest on a home loan tax deductible in NZ? For owner-occupiers: no. Interest on your primary residence is not tax deductible in New Zealand. For residential rental property investors: interest deductibility was phased out and then progressively restored. As of the 2025–26 tax year, investors can deduct 100% of mortgage interest. Confirm current rules with your accountant or IRD guidance.
What happens if I miss a mortgage repayment? Your bank will contact you. Most lenders have hardship policies — if you proactively communicate, they will often grant a repayment holiday or restructure the loan. If you ignore the issue, penalties accumulate and enforcement action (including mortgagee sale) can follow, though this is a last resort.
Can I increase my mortgage? Yes. This is called a “top-up” or refinance. You’ll need to re-qualify with the bank (income, credit, updated valuation), and sufficient equity in the property is required. Common reasons include home renovations, purchasing an investment property, or debt consolidation.
What is a split loan? A split loan divides your mortgage into multiple portions — each with its own rate type and term. For example, part fixed and part floating. This is the most common NZ mortgage structure and balances rate certainty with flexibility.
How does the bank value my property? Banks commission an independent registered valuation or use an automated valuation model (AVM). If the bank’s valuation comes in below the purchase price, the LVR calculation is based on the lower value — which may increase your required deposit. Getting your own valuation before making an offer can avoid surprises.
What to Read Next
- Getting a Mortgage in NZ — the full application process
- How Much Can I Borrow?: borrowing limits and affordability tests
- Fixed vs Floating Mortgage NZ — choosing the right rate type
- NZ Mortgage Rates 2026 — current rates from all major banks
- How Much Deposit Do I Need? — deposit requirements explained
- LVR Restrictions NZ — RBNZ limits and exceptions
- Using KiwiSaver for Your First Home — withdrawing your balance as a deposit