A lot of people think they need to save a separate deposit to buy an investment property. Many of them already have one — sitting untouched in their home. If your property has increased in value since you bought it, or you've paid down a meaningful chunk of your mortgage, there's a good chance the equity you've built is enough to get started.
This article explains how to calculate what's usable, what the lending rules look like, and how the structure of an investment loan differs from the one on your home.
Equity vs usable equity — they're not the same thing
Equity is the difference between what your property is worth and what you owe on it. If your home is worth $900,000 and your mortgage is $450,000, you have $450,000 in equity. But you can't use all of it — lenders won't let you borrow against the full value of a property you live in.
For owner-occupied lending, the maximum LVR (loan-to-value ratio) is 80% — meaning a lender will lend up to 80% of your home's value. Everything above that threshold is what you can draw on. To understand why LVR matters, see our article on what LVR is and how it works.
Usable equity = (80% of your home's value) minus your existing mortgage balance.
On a $900,000 home with a $450,000 mortgage: 80% of $900,000 = $720,000. Less the $450,000 you owe = $270,000 in usable equity. That $270,000 is what you have to work with as a deposit for an investment purchase.
The LVR rules for investment lending
Investment property lending has stricter LVR limits than owner-occupied. The Reserve Bank of New Zealand sets a cap of 70% LVR for residential investment property — which means you need a minimum 30% deposit (or equity) to buy an investment property.
| Property type | Max LVR | Minimum deposit / equity |
|---|---|---|
| Owner-occupied (existing) | 80% | 20% |
| Residential investment (existing) | 70% | 30% |
| New build — owner-occupied | Up to 90% | 10% |
| New build — investment | Up to 80% | 20% |
New builds: the exception worth knowing
New builds are exempt from the RBNZ's standard LVR restrictions. This is deliberate policy — the government wants new housing supply and has carved out more flexible lending conditions to encourage it.
In practice, this means that for a new build investment property, most lenders will go to 80% LVR rather than 70% — so you only need a 20% deposit rather than 30%. Some lenders apply their own internal limits within the exemption, so the ceiling varies, but 80% is a reasonable benchmark for planning purposes.
If you're considering a new build as your first investment, the reduced deposit requirement is a meaningful advantage. The trade-off is that new builds typically carry a price premium and a development risk during construction that established properties don't, so the decision involves more than just the lending terms.
Other exceptions to the 70% rule
The 70% cap applies to the vast majority of residential investment loans, but there are situations where lenders have flexibility:
- New builds as above — RBNZ-mandated exemption, applies across the board
- Bridging finance — short-term lending during a purchase-and-sale overlap can sometimes exceed the standard caps
- Certain commercial or mixed-use properties — these don't fall under the RBNZ residential investor rules at all and are assessed on separate criteria
- Lender-specific exceptions — banks operate within RBNZ speed limits that allow a small percentage of new lending above the standard caps; these are rare, assessed case by case, and not something to plan around
For most investors using equity from an existing home, the 70% rule is the one to design around.
Two ways to access your equity
Once you've established how much usable equity you have, there are two broad ways to deploy it as a deposit for an investment purchase.
Option 1 — Top up your existing loan. You increase your current mortgage by the deposit amount and use those funds for the investment purchase. The investment property then has its own separate loan at the appropriate LVR. This is straightforward from a bank's perspective, but it does mean both properties can end up cross-collateralised — that is, both secured against your home — depending on how the bank structures it.
Option 2 — A separate equity loan on your home. You draw a revolving credit or term loan specifically against the equity in your home, treat that as the deposit, and fund the investment property with a standalone loan secured only against the investment property. This keeps the two securities separate, which gives you more flexibility down the track — if you want to sell the investment property, refinance it independently, or add a third property, clean separation makes all of those easier.
Structure matters here. Cross-collateralisation — where one lender holds both properties as security for a single combined debt — is common but creates complications when you want to sell one property, refinance, or move lenders. The cleaner approach is to keep each property securing only its own debt. This takes more thought upfront but pays off significantly as a portfolio grows. It's worth discussing with an adviser before you sign anything.
How rental income is assessed
When you apply for an investment loan, lenders don't take the rental income at face value. Most will credit somewhere between 70% and 75% of the market rent for serviceability purposes — the remaining 25–30% is treated as a buffer for vacancies, maintenance, rates, and management costs.
This means that if a property rents for $600 per week, a lender might only count $420–$450 per week as income in their affordability assessment. The rest of the debt servicing has to be covered by your other income.
It also means the income assessment is based on market rent — usually confirmed by a property manager's rental appraisal — not what a property happens to be renting for now if it's been underpriced.
Interest-only vs principal and interest
Investment loans are commonly structured on interest-only terms, at least initially. This keeps repayments lower, which can improve cash flow and serviceability for further borrowing. The trade-off is that you're not paying down the principal — so the balance doesn't reduce unless you make extra repayments.
Whether interest-only makes sense depends on your overall strategy. If you're focused on building a portfolio quickly and want to preserve serviceability for future purchases, interest-only can be the right call. If you're buying one investment property and want to own it outright eventually, principal-and-interest may be more appropriate.
Most lenders will offer interest-only terms for a fixed period — typically five years — after which the loan reverts to principal and interest. Planning around that revert date is part of managing the investment sensibly.
A worked example
Your existing home
Investment property purchase (existing residential)
If the same $270,000 were used toward a new build at 80% LVR, the maximum supported purchase price rises to $1,350,000 — though in practice, serviceability (your income vs. total debt) will be the binding constraint long before LVR.
A note on tax
Tax treatment for investment property in New Zealand has changed significantly in recent years. Interest deductibility — the ability to offset mortgage interest against rental income — was phased out and then partially restored, and the rules depend on when the property was purchased and what type it is. New builds have generally received more favourable treatment throughout these changes.
This article isn't the place to work through the specifics, but it's important to factor in. The after-tax cash flow of an investment property can look very different depending on your structure, and it's worth getting an accountant involved alongside your mortgage adviser before you commit to a purchase.
Where to start
The practical first step is a clear picture of your current position: what your home is worth (a bank valuation or recent comparable sales will do), what you owe, and what that leaves you with in usable equity. From there you can work out what purchase price is realistic at the relevant LVR, run the serviceability numbers including rental income, and decide on the right loan structure.
That's exactly the kind of assessment we do at Momentum Partners. We work through the numbers with you, look at the structure options, and give you an honest view of what's achievable — and what isn't yet. If you're considering a first investment property or thinking about using your equity to grow an existing portfolio, it's worth a conversation before you start looking at listings.
Ready to find out what your equity can do?
Let's run the numbers on your position and see what's possible.