An interest-only home loan sounds appealing — lower repayments, better cash flow, more flexibility. And for the right borrower, at the right time, it genuinely is. But for the wrong borrower it's a trap: you pay thousands in interest without reducing your debt by a single dollar. Here's a clear breakdown of how IO loans work, who they actually suit, and what to watch out for in 2026.
What Is an Interest-Only Home Loan?
With a standard principal and interest (P&I) loan, every repayment covers two things: interest charged on your outstanding balance, and a portion of the principal (the amount you borrowed). Over time, your debt reduces.
With an interest-only (IO) loan, your repayments cover only the interest. Your loan balance stays exactly the same. After a 5-year IO period on a $700,000 loan, you still owe $700,000.
IO periods on investment loans can extend up to 10 years, though most lenders apply a 5-year cap in practice. For owner-occupier loans, the maximum is typically 5 years. After the IO period ends, the loan automatically converts to P&I — and your repayments jump, sometimes significantly, because you now have to repay the full principal over the remaining loan term.
How Much Do IO Loans Cost Extra?
IO loans carry a higher interest rate than equivalent P&I loans. The rate premium varies by lender, but in 2026 the spread is typically 0.3%–0.6% p.a. on investment loans, and slightly higher (0.4%–0.7%) on owner-occupier IO loans, as lenders price the additional risk into the rate.
Here's how that plays out on a $700,000 loan over 30 years, comparing 6.30% P&I vs 6.80% IO:
P&I vs IO — $700,000 Loan, 30-Year Term
| P&I (full term) | IO (years 1–5) | Reverts to P&I (years 6–30) | |
|---|---|---|---|
| Monthly repayment | $4,212 | $3,967 | $4,600 |
| vs P&I benchmark | — | Saves $2,940/yr | Costs $4,656/yr extra |
| Loan balance after 5 years | ~$649,000 | $700,000 | — |
| Extra interest over 30 years | — | ~$47,000 total | |
Figures are illustrative based on typical 2026 rates. Exact figures depend on your lender and rate.
The "savings" in the IO period are real — but they come at a steep long-term cost. You pay more interest overall, and your repayments jump sharply when P&I kicks in.
Who Are IO Loans Actually For?
IO loans are not inherently bad products. They suit specific situations well.
Property investors
This is the primary use case, and it's legitimate. For an investment property, interest is tax-deductible. Principal repayments are not. An investor on a high marginal tax rate can effectively reduce the after-tax cost of holding a property by keeping repayments interest-only — maximising the deductible component.
Investors also typically focus on total return (rental income + capital growth) rather than equity building. Keeping repayments low frees up cash flow to maintain the property, service other loans, or invest elsewhere. See our guide to investment property tax deductions for more on what you can claim.
Borrowers managing short-term cash flow pressure
If you're between jobs, on parental leave, or dealing with an unexpected expense, temporarily switching to IO can reduce your monthly obligation while you stabilise. This is different from taking IO from the start — it's using IO as a planned, short-term tool.
People buying off-the-plan or building
During a construction period, IO loans are common because the property isn't generating income yet and the full value isn't built. Many construction loans run IO during the build phase then convert to P&I on completion.
Sophisticated borrowers with a clear strategy
Some borrowers hold IO loans while directing surplus cash into an offset account — achieving similar debt reduction while maintaining liquidity. This requires discipline and works best with an offset-linked IO loan. Without that discipline, the money tends to get spent.
Who Should Avoid IO Loans?
IO loans are generally not suitable for:
- First home buyers who aren't investors — you're not building any equity during the IO period, which is particularly risky in a flat or declining market
- Borrowers already at the limit of their borrowing capacity — the P&I repayment jump at the end of the IO period can be a significant shock
- Anyone who won't use the cash flow benefit strategically — if you're not directing the savings toward investments or debt reduction, you're simply paying more for the same loan
- Borrowers planning to sell within a few years — unless you're confident the property will appreciate enough to cover the higher interest cost
The Repayment Jump: What Happens When IO Ends?
This catches many borrowers by surprise. When the IO period ends, your repayments are recalculated based on:
- The same loan balance (unchanged — you paid no principal)
- The remaining loan term (now shorter — e.g. 25 years remaining if you had 5 years IO on a 30-year loan)
- The then-current interest rate (which may be higher or lower than today)
The Jump in Numbers
$700,000 loan, 5 years IO at 6.80%, then reverts to P&I:
- IO period monthly repayment: $3,967
- P&I repayment from year 6 (at 6.30%): $4,600
- Jump: +$633/month (+$7,596/year)
This jump occurs even if rates don't change. If rates have risen, the jump is larger.
Given the RBA has already delivered two rate hikes in 2026 — February (to 3.85%) and March (to 4.10%) — borrowers approaching the end of IO periods should be stress-testing this transition now.
APRA's Limits on IO Lending
APRA monitors IO lending closely. After concerns about investor overexposure in 2017, it introduced a cap requiring IO loans to remain below 30% of new residential mortgage lending. That formal cap has since been lifted, though APRA continues to monitor IO lending levels. Lenders remain cautious — most apply stricter serviceability assessments to IO applications, effectively requiring borrowers to demonstrate they can afford the P&I repayment from day one.
This means you can't use IO to borrow more than you could on P&I. Lenders assess your ability to repay at the higher P&I amount, regardless of what your actual IO repayment will be.
IO and Mortgage Stress in 2026
With 1.3 million Australian households projected at risk of mortgage stress following the two 2026 rate hikes (Roy Morgan Research, January 2026), some borrowers are looking at switching from P&I to IO as a relief measure.
This can work as a short-term strategy — switching a $700,000 loan from P&I to IO reduces repayments by roughly $200–$300/month, assuming a similar rate. In practice the saving may be smaller, as IO rates typically carry a premium over P&I. But it comes with trade-offs:
- Your lender may charge a higher rate on the IO portion
- You stop building equity — potentially problematic if you need to refinance later
- The IO period has to end somewhere, and the P&I repayment jump will be steeper
- Some lenders don't allow existing P&I loans to switch mid-term without a new application
If you're under genuine financial pressure, hardship assistance from your lender (available under the National Credit Code) or refinancing to a lower rate may achieve more than IO switching without the long-term cost. See our full guide on 7 strategies to cope with mortgage stress in 2026. Speaking to a mortgage broker before making this change is strongly recommended.
IO vs Offset: What's the Difference?
A common point of confusion: IO loans reduce your repayment by removing the principal component. An offset account reduces the interest you pay without changing your repayment structure.
P&I + offset: You make full repayments (including principal), but surplus cash in the offset account reduces the interest calculated each month. Your debt reduces. Your equity builds.
IO + offset: Your repayments are lower, and any cash in the offset reduces interest — but your principal balance stays the same unless you make voluntary extra repayments.
The P&I + offset combination is generally more effective at building wealth over the long term. The IO + offset can work for disciplined investors, but requires a clear purpose and consistent execution.
Written by Amit Narang, Mortgage Broker | Credit Representative 558902 of Outsource Financial Pty Ltd (ACL 384324)
Sources: APRA Quarterly ADI Performance Statistics (apra.gov.au); RBA Financial Stability Review, October 2025 (rba.gov.au); Canstar IO vs P&I rate comparison 2026; ATO — rental property deductions guide (ato.gov.au); MoneySmart — interest-only home loans (moneysmart.gov.au); Roy Morgan Mortgage Stress Research, January 2026 (roymorgan.com).
Considering an Interest-Only Loan? Let's Run the Numbers.
Whether you're an investor weighing up IO for tax purposes or an owner-occupier looking to reduce repayment pressure, we can model both scenarios and show you the long-term cost — at no charge and no obligation.
Get a Free Loan Assessment