Key Takeaway

Principal and interest (P&I) loans require you to repay both the loan amount and interest each month, building equity and reducing your debt over time. Interest-only loans let you pay just the interest for a set period (typically 1 to 5 years), keeping repayments lower initially but leaving the full loan balance owing. P&I loans cost less over the life of the loan and are the standard choice for owner-occupiers, while interest-only may suit investors or those managing short-term cash flow needs.

Introduction

Choosing between principal and interest and interest-only repayments is one of the first structural decisions you will make when taking out a home loan in Australia. The choice affects your monthly budget, how quickly you build equity, and how much you pay in total interest over the life of the loan. Understanding the seven key differences below will help you match the right repayment structure to your financial situation and property goals.

1. How Principal and Interest Repayments Work

With a principal and interest (P&I) loan, every monthly repayment includes two components: a portion that reduces the loan balance (the principal) and a portion that covers the interest charged by the lender. Early in the loan term, most of each repayment goes toward interest, but as the principal shrinks, more of each payment reduces the debt. By the end of the loan term (typically 25 or 30 years), the loan is fully repaid. This structure is the default for most Australian home loans and is strongly preferred by lenders and regulators for owner-occupiers. According to ASIC MoneySmart, P&I repayments ensure you are steadily paying down the debt and building equity in the property.

2. How Interest-Only Repayments Work

An interest-only loan lets you pay only the interest charged each month for a set period, usually between one and five years. During the interest-only period, your repayments are lower because you are not reducing the principal, and the full loan balance remains owing. Once the interest-only period ends, the loan typically reverts to principal and interest repayments, and your monthly payment jumps because you must now repay the entire principal over the remaining loan term. Interest-only loans are more common among property investors who may want to maximise tax deductions or manage cash flow while the property appreciates or generates rental income.

3. Monthly Repayment Comparison

Interest-only repayments are significantly lower than principal and interest repayments during the interest-only period. For example, on a $500,000 loan at a 6 per cent interest rate, an interest-only repayment might be around $2,500 per month, while a P&I repayment on a 30-year term would be approximately $3,000 per month. The lower repayment can improve short-term cash flow, but remember that the principal still needs to be repaid eventually. Once the interest-only period ends, the P&I repayments on the remaining term will be higher than if you had chosen P&I from the start, because you now have fewer years to repay the same amount.

4. Total Interest Cost Over the Life of the Loan

Choosing interest-only means you pay more interest over the life of the loan. Because the principal balance is not reduced during the interest-only period, you continue to pay interest on the full original loan amount for longer. Using the $500,000 loan example above, choosing interest-only for five years and then switching to P&I for the remaining 25 years could cost tens of thousands of dollars more in total interest compared to a 30-year P&I loan from the outset. Foundational finance texts such as Principles of Finance explain that minimising the time interest accrues on principal is a core strategy for reducing borrowing costs.

5. Building Equity and Reducing Debt

Principal and interest loans build equity from day one. Every repayment reduces the amount you owe, increasing the portion of the property you own outright. This is particularly important for owner-occupiers who want to own their home sooner or access equity later for renovations or other purposes. Interest-only loans do not build equity through repayments during the interest-only period. Equity can still grow if the property value increases, but you rely entirely on capital growth rather than debt reduction. If property values stagnate or fall, an interest-only borrower may find themselves with little or no equity, which can complicate refinancing or selling.

6. Who Should Consider Interest-Only Loans

Interest-only loans are rarely suitable for first home buyers or standard owner-occupiers, as they delay debt reduction and cost more in the long run. They are more commonly used by property investors who can claim the interest as a tax deduction against rental income and who may plan to sell the property before the interest-only period ends. Some borrowers also use interest-only periods to manage temporary cash flow constraints, such as during parental leave or while renovating a property, with the intention of switching to P&I repayments as soon as their circumstances improve. APRA prudential standards require lenders to assess serviceability on the basis that the loan will revert to principal and interest repayments, so you must be able to afford the higher repayments when the interest-only period ends.

7. Switching Between Repayment Types

Most Australian lenders allow you to switch from interest-only to principal and interest repayments at any time during the interest-only period without penalty, though you should confirm this with your lender. Switching to P&I sooner reduces the total interest cost and helps you build equity faster. Conversely, refinancing from a P&I loan to an interest-only structure is possible but typically requires a new application and serviceability assessment. Lenders are more cautious about approving interest-only loans for owner-occupiers, and some will only offer them to investors or borrowers with substantial equity. Rates on interest-only loans can also be slightly higher than P&I rates, reflecting the higher risk to the lender.

Read also: How to Structure Investment Property Loans in Australia

Practical Tips

  • Run a repayment comparison using your own loan amount and interest rate to see the real difference in monthly repayments and total interest cost. Most lender websites and MoneySmart offer free calculators.
  • If you are considering interest-only to manage short-term cash flow, model the higher repayments that will apply once the interest-only period ends and ensure you can afford them.
  • For investors, speak to a qualified tax professional to understand how interest-only repayments interact with negative gearing and capital gains tax when you eventually sell the property.
  • Remember that interest rates quoted in advertising differ from the comparison rate, which includes most fees and charges. Verify current rates and terms with a licensed mortgage broker or lender before deciding.

Common Mistakes to Avoid

  • Choosing interest-only because the initial repayments are lower, without considering the higher total cost and the repayment shock when the interest-only period ends.
  • Assuming interest-only is always better for investors. Paying down principal can still be beneficial if it allows you to access equity sooner or reduce debt before selling.
  • Forgetting that lenders will assess your ability to service principal and interest repayments even if you apply for interest-only, so your borrowing capacity may be lower than you expect.
  • Not reviewing your repayment structure regularly. Many borrowers remain on interest-only by default when switching to P&I earlier would save them money.

Frequently Asked Questions

Can I get an interest-only loan as a first home buyer?
It is difficult but not impossible. Most lenders prefer P&I loans for owner-occupiers, and APRA prudential standards limit the proportion of interest-only lending banks can offer. If you do qualify, you will need substantial equity or a strong financial position.

Will I pay a higher interest rate on an interest-only loan?
Often, yes. Lenders typically charge a premium of 0.10 to 0.30 percentage points on interest-only loans compared to P&I loans, reflecting the higher risk.

What happens if I cannot afford the P&I repayments when the interest-only period ends?
You may be able to extend the interest-only period or refinance to a longer loan term, but this is not guaranteed and depends on your circumstances and the lender’s policies. Speak to your lender or a licensed mortgage broker well before the interest-only period expires.

Can I make extra repayments on an interest-only loan?
Yes, most lenders allow you to make additional repayments into an offset account or redraw facility during the interest-only period, effectively reducing the principal and the interest charged, though the structure of the loan remains interest-only unless you formally switch.

Conclusion

Principal and interest loans are the standard, lower-cost choice for owner-occupiers and offer the certainty of building equity and paying off debt over time. Interest-only loans can suit specific situations, particularly for investors or during temporary cash flow constraints, but come with higher long-term costs and require careful planning for the repayment increase when the interest-only period ends. Assess your financial goals, model the repayments and total cost for both structures, and consult a licensed mortgage broker or lender to confirm which option best fits your circumstances.

General Advice Warning

The information in this article is general in nature only and does not consider your personal objectives, financial situation, or needs. It is not personalised financial, lending, or legal advice. Interest rates, loan terms, eligibility, fees, and government schemes vary by lender, product, state or territory, and your individual circumstances. Advertised rates differ from the comparison rate, which includes most fees and charges. Rates and policies are current as of July 2026 and change frequently. You should verify current terms with a licensed mortgage broker or lender, consider obtaining personal advice from a licensed financial professional, and refer to ASIC MoneySmart for independent guidance before making any financial decision.