Interest-only loans are one of the most debated topics in Australian property investment. Praised by some investors for their cash flow benefits and tax efficiency, criticised by others for their higher rates and the risk of never reducing debt — the truth, as usual, lies somewhere in between. Here’s what you need to know before deciding if an interest-only loan is right for your portfolio.
What Is an Interest-Only Investment Loan?
With a standard principal and interest (P&I) loan, your repayments cover both the interest charged and a portion of the loan balance. Over time, your debt reduces and you build equity through repayments.
With an interest-only loan, your repayments cover only the interest component for a set period — typically 1 to 5 years (some lenders allow up to 10 years for investors). During this period, you are not reducing the loan balance at all. At the end of the interest-only period, the loan reverts to principal and interest repayments — usually over the remaining loan term, which means higher P&I repayments than if you had been paying P&I from day one.
The Case For Interest-Only Investment Loans
Lower Repayments, Better Cash Flow
The most obvious benefit is lower monthly repayments. On a $600,000 investment loan at 6.5% p.a., the monthly repayments are approximately:
- Interest-only: ~$3,250/month
- Principal and interest (30-year term): ~$3,792/month
That’s a $542/month difference — nearly $6,500 per year. For investors managing multiple properties or tight cash flow, this can be the difference between a portfolio being self-sustaining and requiring top-ups from personal income.
Maximising Tax Deductions
For investment properties, interest on your loan is generally tax-deductible. Since interest-only repayments are entirely interest (by definition), every dollar of your repayment may be deductible. This makes interest-only loans particularly appealing to investors in higher tax brackets who want to maximise deductions.
Important: Tax deductibility depends on the loan being used for income-producing purposes. Always consult your accountant before structuring loans for tax purposes.
Capital Growth Focus
Some investors argue that actively reducing an investment loan balance is inefficient. If the property is growing in value at 5–7% per annum and the loan rate is 6.5%, you’re better off preserving cash flow and directing surplus funds toward your owner-occupied mortgage (which is not tax-deductible) or your next investment purchase. Interest-only on the investment property, P&I on the home loan, is a common strategy.
The Case Against Interest-Only Investment Loans
Higher Interest Rates
Interest-only investment loans carry higher rates than P&I investment loans — typically 0.2% to 0.5% more. Over the long term, this premium adds up. The total interest paid over the life of an IO loan is significantly higher than a comparable P&I loan.
No Equity Build-Up Through Repayments
You’re not building equity through repayments — only through capital growth. In a flat or declining market, this means your net position doesn’t improve. When the interest-only period ends, you still owe the full original loan amount.
Repayment Shock at Revert
When the interest-only period ends, your loan reverts to P&I repayments calculated over the remaining term. Since the balance hasn’t reduced, and the remaining term is now shorter, these P&I repayments can be significantly higher than if you’d been on P&I from the start. This “repayment shock” catches many investors off guard.
When Does an Interest-Only Loan Make Sense?
Interest-only loans tend to make the most sense when:
- You have an owner-occupied home loan that is not tax-deductible — it makes more sense to pay down the non-deductible debt first while keeping the investment loan on interest-only
- You are in a high income tax bracket and the deductions deliver significant tax savings
- You are in a growth phase and want to preserve cash flow for your next purchase
- You have a clear exit strategy — such as selling the property before the interest-only period ends
- The property cash flows positively even on a P&I basis, and you’re using IO purely for tax efficiency
Questions to Ask Before Choosing Interest-Only
- Do I have an owner-occupied home loan? If yes, IO on the investment and P&I on the home loan is often the right approach.
- What is my tax bracket? The higher your income, the more valuable the interest deductions.
- What happens when the IO period ends? Can I service the higher P&I repayments, or will I need to refinance?
- Is the property cash flow positive or negative? If negatively geared, does that align with my overall tax strategy?
- What is my investment timeframe? If you plan to sell within 5–7 years, IO may be appropriate. If holding long-term, P&I builds a stronger equity position.
Get the Right Advice for Your Situation
The interest-only decision is one of the most important loan structuring choices you’ll make as an investor — and it interacts closely with your tax position, cash flow, and long-term portfolio strategy. At Tenfold Property Finance, we help you understand the full picture before choosing your loan structure.
Back to: The Ultimate Guide to Investment Property Loans in Australia