Every property investment loan locks in a return profile from the moment you sign. Not because of the interest rate (that changes), but because the loan structure you choose determines how much you can deduct each year, how fast you build equity, and when you can access capital for the next purchase.
Most guides treat loan selection as a neutral menu. Pick fixed or variable, interest-only or principal and interest, move on. The reality is that each structure creates a different tax and cash-flow trajectory that compounds over the life of the loan. Getting this decision wrong does not just cost you money month to month. It shapes your entire portfolio strategy.
Choosing the right type of loan can be just as important as choosing your investment property. Here is how each option works, what it costs you, and where it fits.
What is a property investment loan?
A property investment loan is a home loan taken out specifically to fund the purchase of an investment property. If you plan to buy a property, rent it out, and earn income from tenants, this is the loan product you apply for.
The application process follows a similar path to applying for an owner-occupier home loan. You provide income documentation, asset and liability statements, and details about the property. Lenders assess your serviceability, which includes factoring in expected rental income.
Investment property loans can be used to purchase land, houses, apartments, or commercial property. The common thread is that you earn income through rent while paying interest on the borrowed amount.
Where investment loans differ from owner-occupier loans is in the tax treatment. Interest on an investment loan is tax-deductible. That deduction is the reason loan structure matters so much: different structures produce different deduction profiles over time.
The three loan types Australian investors use
Three structures dominate the Australian investment lending market: interest-only, principal and interest, and equity loans. Each creates a distinct cash-flow and tax profile.
| Interest-only | Principal & interest | Equity loan | |
|---|---|---|---|
| Monthly repayments | Lower (interest only) | Higher (interest + principal) | Varies (depends on structure) |
| Tax-deductible interest | Maximum, stays flat | Shrinks over time | Depends on loan drawn |
| Equity build from repayments | None | Yes, grows each year | Uses existing equity |
| Best for | Cash-flow and deduction maximisation | Long-term wealth building | Portfolio expansion |
Interest-only loans: lower repayments, maximum deductions, zero equity build
Interest-only loans are the most common type of investment property loan in Australia. The structure is straightforward: you pay only the interest component each month. The principal balance stays untouched.
Two advantages drive their popularity.
First, cash flow. Regular loan repayments are lower because you are only paying interest, which increases your cash flow. For a negatively geared property, that gap between a lower repayment and what you would pay on a P&I loan can be the difference between a manageable hold and a strained one.
Second, tax deductions. You maximise your tax-deductible interest expense on your investment property because the full loan balance remains outstanding. Every dollar of each repayment is deductible. None of it goes toward non-deductible principal reduction.
The trade-off is equity. You don't build any equity with your regular interest repayments. Your ownership stake in the property only grows if the property increases in value over time. If the market is flat or declining, you are paying interest on an asset that is not generating equity from either direction.
There is a time limit. Interest-only loans are usually only available for 5-year terms. After that period, you need to take out another interest-only loan, switch to principal and interest, or move to an equity loan. That 5-year window is not optional. It is a structural feature of the Australian lending market, and your exit plan from an IO term should be mapped before you enter one.
For a deeper comparison of how these two repayment structures play out over a full loan term, see our guide on interest-only vs principal and interest for investment property.
Principal and interest loans: equity growth with a shrinking tax benefit
A principal and interest (P&I) loan splits each repayment between reducing the loan balance and covering interest charges. The result is a loan that gradually pays itself off.
The equity benefit is clear. You increase your equity in your property over time as you make regular repayments and your loan balance reduces. At the end of the loan term, you own the property outright. That is an unencumbered asset generating rental income with no debt service.
The tax cost is equally clear. Your tax-deductible interest expense reduces over time as your investment property loan reduces. In year one, most of your repayment is interest and therefore deductible. By year twenty, most of your repayment is principal and not deductible. The deduction curve slopes downward for the entire life of the loan.
This is the core tension between the two structures. Interest-only preserves the full deduction but builds no equity through repayments. P&I builds equity steadily but gives you less to claim each year.
Neither is objectively better. The right choice depends on whether you are optimising for cash flow now or asset accumulation over a longer horizon. An investor planning to hold a single property for 25 years has different priorities than someone building a portfolio across multiple purchases over 10 years.
Equity loans: using your home to fund the next purchase
The third structure lets you skip the savings phase entirely for a second or third property. Equity loans require you to use the equity in one property, such as your residential home, as the deposit for an investment property purchase.
The mechanics work like this: your existing property is valued, and the lender calculates how much equity sits above the loan balance. Most lenders will let you borrow up to 80% of the equity in another property to fund the investment purchase. That 80% threshold is the same loan-to-value ratio (LVR) ceiling that applies across most Australian residential lending.
The portfolio acceleration effect is significant. Equity loans can increase your borrowing power and help you build a property portfolio more quickly. Instead of saving a fresh deposit from income over several years, you redirect the capital gains from property one into the deposit for property two.
The risk runs in the same direction. If property values fall, the equity you have borrowed against shrinks. You can end up with two properties and insufficient equity to support the combined debt. If you are considering refinancing your investment property to access equity, understand the valuation risk before committing.
Deposit requirements and Lenders Mortgage Insurance
The deposit threshold for investment property is higher than for owner-occupier purchases. You need 20% of the purchase price as a deposit to avoid Lenders Mortgage Insurance (LMI).
LMI protects the lender, not you. It is a one-off premium added to your loan or paid upfront, and it can run into thousands of dollars on a typical investment purchase. Falling short of the 20% mark does not prevent you from borrowing, but it adds a cost that does nothing for your return.
Our investment property deposit guide covers how to calculate the full upfront cost, including stamp duty, legal fees, and inspection costs on top of the deposit itself.
Loan structure is a tax decision
This is the point most borrowers miss at the application stage. Your loan type is not just a financing decision. It is a tax decision that compounds over the life of the investment.
An interest-only loan on a $600,000 property keeps the full balance outstanding, preserving the maximum deductible interest expense year after year. A P&I loan on the same property steadily erodes that deduction as the balance falls. Over a 10-year hold, the cumulative difference in claimable interest can be substantial.
That does not make interest-only universally superior. The investor who pays down a P&I loan for 15 years owns an unencumbered asset generating gross rental income with no interest expense offsetting it. Their taxable income from the property is higher, but so is their net cash flow.
The strategic question is: do you want to maximise deductions while you are in a high tax bracket and rely on capital gains for wealth creation? Or do you want to build a debt-free income stream that compounds without leverage?
Your answer to that question should drive your loan structure. Not the other way around.
If you are still weighing up the broader question of whether property is the right asset class for your situation, our guide to buying investment property in Australia covers the full decision framework.
Risks to understand before borrowing
Borrowing to invest in property is classified as a high-risk strategy. That classification comes from ASIC's Moneysmart, and it applies regardless of which loan structure you choose.
The risk is amplified with interest-only loans specifically. Because IO repayments do not reduce the principal, you don't build any equity through repayments. If the property's value drops during your hold period, you owe more than the property is worth. There is no principal reduction acting as a buffer.
With P&I loans, falling values still hurt, but the shrinking loan balance provides a margin. After five years of P&I repayments, you have built equity through repayments even if the market has been flat.
Three practical risk factors to assess before committing:
- Rate rises. Your serviceability is tested at a buffer above the current rate, but sustained increases still compress cash flow. Model your repayments at 2% above the current rate before signing.
- Vacancy. Rental income is not guaranteed. Budget for at least four weeks of vacancy per year when stress-testing affordability.
- The 5-year IO cliff. When an interest-only term expires, repayments jump significantly as the loan reverts to P&I on the remaining term. Know what that number looks like before you start.
FAQ
What is a property investment loan?
A property investment loan is a home loan taken out specifically to fund the purchase of an investment property. It can be used to purchase land, houses, apartments, or commercial property. Interest payments on the loan are tax-deductible.
What deposit do I need for an investment property loan in Australia?
You need 20% of the purchase price as a deposit to avoid Lenders Mortgage Insurance. You can borrow with less than 20%, but LMI will be added to your costs. See our full deposit guide for a breakdown.
Should I choose interest-only or principal and interest for an investment loan?
It depends on your strategy. Interest-only loans maximise tax-deductible interest expense and improve cash flow, but build no equity through repayments. P&I loans build equity over time but your deductible interest shrinks each year. Compare both options in our IO vs P&I guide.
Can I use equity in my home to buy an investment property?
Yes. Equity loans let you use the equity in an existing property as the deposit for an investment property purchase. Most lenders allow you to borrow up to 80% of your available equity.
Is borrowing to invest in property risky?
Borrowing to invest is classified as a high-risk strategy. The main risks include interest rate increases, property value declines, vacancy periods, and the repayment jump when interest-only terms expire after their typical 5-year limit.