How principal and interest repayments work
With a principal and interest (P&I) loan, each repayment is split between reducing the amount borrowed (the principal) and covering the interest charged on the outstanding balance. Early in the loan term, a larger portion of each repayment typically goes toward interest, since interest is calculated on a larger outstanding balance; over time, as the balance reduces, a greater share of each repayment goes toward principal. This structure is designed so that, by the end of the agreed loan term, the entire balance is repaid in full, provided repayments are made as scheduled. P&I is the default repayment structure for most Australian home loans and is typically required by lenders for owner-occupied lending unless a specific interest-only arrangement is requested and approved. Because the balance steadily reduces, P&I loans generally result in less total interest paid over the life of the loan compared with an equivalent interest-only structure. This nuance is easy to overlook but can materially affect the outcome for a borrower comparing options.
How interest-only repayments work
With an interest-only loan, repayments during the interest-only period cover only the interest charged, meaning the loan balance does not reduce during that time. Interest-only periods are typically set for a limited number of years, after which the loan usually reverts to principal and interest repayments for the remaining term, often resulting in a repayment increase at that point since the remaining principal must be repaid over a shorter remaining timeframe. Interest-only arrangements are more commonly associated with investment lending, where investors may value lower repayments and other financial considerations, though they can be available for owner-occupied loans in certain circumstances subject to lender approval. Because the balance doesn't reduce during the interest-only period, more interest typically accrues in total over the life of the loan compared with a fully principal and interest structure over the same term. Taking time to understand this before applying can help set realistic expectations.
Comparing the total cost over the loan term
Because P&I repayments steadily reduce the balance interest is calculated on, they typically result in a lower total interest cost over the life of the loan compared with an interest-only structure of the same rate and term, assuming both eventually repay the same principal. An interest-only period effectively defers principal reduction, meaning interest continues to accrue on the full balance for longer, which can add a meaningful amount to the total cost, particularly for longer interest-only periods. It's also worth considering that once an interest-only period ends, repayments generally increase, sometimes considerably, since the remaining principal must be repaid over a shorter period than originally planned. Borrowers weighing up the two structures should look beyond the size of near-term repayments and consider the total interest paid and the repayment increase that typically follows an interest-only period. It's a detail worth clarifying directly with a lender or broker if anything is unclear.
Why borrowers choose interest-only
Borrowers sometimes choose interest-only repayments to manage cash flow in the short term, such as during a period of reduced income, renovation works, or when directing funds toward another financial priority. Investors may use interest-only periods for reasons related to their broader financial strategy, though the specific tax treatment of any loan should be discussed with a qualified tax professional rather than assumed. It's worth noting that lenders typically assess interest-only applications with additional scrutiny, since the lack of principal reduction during that period represents a different risk profile. Approval for an interest-only period, and its length, is generally at the lender's discretion and subject to the borrower continuing to meet servicing requirements, so it isn't automatically available on every loan or to every borrower. Small differences here can add up meaningfully over the full term of a loan. Borrowers who ask about this upfront are typically better placed to avoid surprises later.
Deciding which structure suits your situation
Choosing between P&I and interest-only typically depends on your financial goals, cash flow needs, and how comfortable you are with a longer period of unreduced principal. Borrowers focused on paying off their home as efficiently as possible generally benefit from P&I repayments from the outset, since every repayment contributes to reducing the balance and the associated interest. Those needing temporary repayment relief, or pursuing a specific financial strategy, might consider a limited interest-only period, while being mindful of the repayment increase and higher total interest cost that typically follow. It's worth modelling both scenarios, including how repayments change after an interest-only period ends, before deciding, and discussing the options with a broker or lender to understand what's available given your specific circumstances and loan type. Borrowers who ask about this upfront are typically better placed to avoid surprises later. This is one of the finer details that a good broker can help talk through.
Key points
- P&I repayments reduce the loan balance with every payment made
- Interest-only repayments cover interest only, leaving the balance unchanged
- Interest-only typically increases total interest paid over the loan's life
- Repayments usually increase once an interest-only period ends
- Interest-only approval is generally at the lender's discretion, not automatic
Frequently asked questions
Does interest-only mean I never pay off the loan?
No. Interest-only typically applies for a limited period, after which the loan usually reverts to principal and interest repayments for the remaining term, so the balance still needs to be repaid, generally with higher repayments after the switch.
Is interest-only cheaper overall?
Not usually. While repayments during the interest-only period are typically lower, the loan balance doesn't reduce during that time, which generally means more total interest is paid over the life of the loan compared with principal and interest.
Can owner-occupiers get interest-only loans?
In some cases, yes, though interest-only is more commonly associated with investment lending. Approval for owner-occupied interest-only arrangements is typically at the lender's discretion and may be subject to additional assessment criteria.