Unlock the Secrets to Investment Loan Fundamentals

An investment loan is not a single product but a collection of choices that shape your capacity to grow a portfolio.

The borrowing structure, repayment type, and deposit strategy you select before settlement will influence your tax position, cash flow, and ability to acquire additional properties over time. These decisions are made once but compound across years.

How Interest-Only Repayments Affect Cash Flow and Tax

Interest-only repayments reduce your monthly commitment by removing the principal component. This preserves cash flow while interest remains tax-deductible against rental income. Principal repayments do not attract a deduction.

Consider a buyer who secures an interest-only loan for a two-bedroom apartment in Clayton. Monthly repayments sit around $2,400 on an interest-only basis, compared to approximately $3,100 if structured as principal and interest. The difference, roughly $700 each month, remains available for portfolio growth, property maintenance, or managing vacancy periods. After five years, the loan reverts to principal and interest unless refinanced or extended. The original loan balance remains unchanged, which means equity growth depends entirely on capital appreciation and any further deposits made voluntarily.

Interest-only periods typically run for one to five years initially, with some lenders offering longer terms depending on the borrower's profile and the loan-to-value ratio. Melbourne's inner and middle-ring suburbs continue to experience low vacancy rates, but periods without a tenant still require the investor to service the full loan from their own income.

Variable or Fixed: What the Rate Type Controls

A variable rate adjusts in line with the lender's cost of funds and broader monetary policy. A fixed rate locks the interest cost for a set period, usually between one and five years.

Variable rates on investment loans allow access to offset accounts and unlimited additional repayments without penalty. Fixed rates offer certainty over repayment amounts but typically restrict offset functionality and apply break costs if the loan is repaid or refinanced before the fixed term ends. Most lenders calculate break costs based on the difference between your fixed rate and the current wholesale funding rate, multiplied by the remaining term and outstanding balance.

Split loan structures combine both rate types across the same facility. A borrower might fix 50 per cent of the loan amount for three years while leaving the remainder on a variable rate with an offset account attached. This approach balances repayment certainty with flexibility, though it requires assessment of how much cash flow protection is genuinely required versus how much liquidity you want to retain.

The Loan-to-Value Ratio and Its Influence on Borrowing Costs

Loan-to-value ratio is the loan amount expressed as a percentage of the property's value at purchase. An LVR above 80 per cent generally triggers Lenders Mortgage Insurance, which is a one-off premium calculated on a sliding scale and added to the loan balance or paid upfront.

LMI premiums vary by lender, loan amount, and LVR. A loan amount at 90 per cent LVR will attract a materially higher premium than one at 85 per cent. Some lenders cap investment lending at 90 per cent LVR, others at 95 per cent, and a few will not lend above 80 per cent without additional security. The premium itself is not tax-deductible in the year it is paid but can be claimed over five years or the life of the loan, depending on the structure.

Beyond LMI, a higher LVR increases the risk weighting applied by the lender under APRA's Prudential Standard APS 112. This feeds into the lender's capital costs, which in turn influences the interest rate offered. Investment loans at the same LVR as owner-occupied loans attract a higher rate, typically between 0.30 and 0.70 percentage points depending on the lender and whether the loan is interest-only or principal and interest.

Serviceability Assessment and the Debt-to-Income Constraint

Lenders assess your ability to service an investment loan by calculating your net income, deducting existing commitments, and testing the loan repayment at a rate at least 3.0 percentage points above the actual product rate. This buffer has been in place since late 2021 and applies to all new borrowers through authorised deposit-taking institutions.

Rental income is included in the assessment, though most lenders apply a discount or haircut to account for vacancy, property management fees, and periods without a tenant. The discount varies by lender but typically sits between 20 and 30 per cent of the gross rent. If the property generates $2,400 per month in rent, the lender might assess serviceability using $1,680 to $1,920 per month.

From February 2026, APRA introduced a debt-to-income lending limit. Each lender may allocate up to 20 per cent of new investor loans to borrowers with total debt of six times their gross income or more. The limit applies separately to investment lending and is measured quarterly across each institution. Borrowers with debt below six times income are unaffected. For those near or above the threshold, loan size may be constrained unless income increases or other debts are reduced before application.

How Deposit Source and Genuine Savings Are Assessed

Lenders distinguish between genuine savings and non-genuine savings. Genuine savings are funds accumulated over at least three months through regular income, held in your own account. Non-genuine savings include one-off gifts, proceeds from asset sales, or funds that appear suddenly without a clear savings pattern.

Some lenders require genuine savings to make up at least 5 per cent of the purchase price if your deposit is below 20 per cent. Others accept equity from an existing property as the full deposit without requiring additional cash savings. Where equity is used, the lender values the existing property and calculates available equity as the difference between the property's current value and the outstanding loan balance, less a buffer typically set at 20 per cent of the property's value.

For a borrower holding a property in Mount Waverley with no outstanding debt, equity can be released by taking out a new loan or increasing an existing facility secured against that property. The released funds then form the deposit for the investment purchase. This approach avoids the need to accumulate cash savings but does increase total borrowing and must still satisfy the lender's serviceability assessment.

Tax Deductions Beyond Interest: What Can Be Claimed

Interest on borrowings used to acquire or hold a rental property is deductible in full, provided the property is rented or genuinely available for rent. Other deductible expenses include property management fees, council rates, insurance, repairs, and depreciation on the building and fixtures.

Borrowing costs, such as loan establishment fees, valuation fees, and mortgage broker fees, can be claimed over five years or the life of the loan, whichever is shorter. Legal fees related to the purchase are generally not deductible but form part of the cost base for capital gains tax purposes when the property is sold.

Stamp duty on the property purchase is also added to the cost base rather than claimed as a deduction. LMI premiums can be claimed over five years or the life of the loan. Property depreciation is calculated by a quantity surveyor and claimed annually, though it can trigger capital gains adjustments on sale if the property was acquired after certain dates.

For properties acquired after 12 May 2026, other than eligible new builds, any net loss after deductions can only be offset against income from other residential rental properties or carried forward to future years. Properties held at that date, or under contract at 7:30pm AEST on that date, continue to allow full deduction of losses against all income. The restriction does not affect the deductibility of individual expenses, only the ability to offset a net loss against salary or other non-property income.

The Role of Offset Accounts in Investment Loan Structures

Offset accounts are transaction accounts linked to a variable rate loan. The balance in the offset account reduces the interest charged on the loan without making a formal repayment.

For an investment loan, parking surplus cash in an offset account reduces the interest cost but does not reduce the deductible interest. The ATO treats the loan balance as unchanged for tax purposes, which means the full interest on the original loan amount remains deductible even though the actual interest charged is lower.

This structure is often used where a borrower has surplus cash but wants to maintain maximum deductible debt on the investment property while preserving liquidity. Offset accounts are generally available only on variable rate loans. Fixed rate products rarely offer offset functionality, and where they do, the offset benefit is often partial rather than 100 per cent.

Refinancing to Access Equity for Further Investment

Refinancing an existing investment loan can release equity for a subsequent purchase without requiring additional cash savings. The lender revalues the property, calculates available equity, and increases the loan balance to release funds.

Equity release is subject to the lender's maximum LVR policy and the borrower's serviceability at the time of refinance. If the original property has increased in value and the loan balance has reduced, the amount of accessible equity grows. Refinancing also provides an opportunity to secure a lower interest rate, switch from interest-only to principal and interest or vice versa, or consolidate multiple loans.

Break costs may apply if refinancing out of a fixed rate loan before the fixed term ends. These costs are calculated by the original lender based on the difference between your fixed rate and the lender's current wholesale funding cost, multiplied by the remaining term. The amount can be substantial if rates have fallen since the fixed term began. Refinancing solely to access equity or secure better loan features should be assessed against any break costs and application fees involved.

Portfolio Growth and the Importance of Loan Structure from the Start

The structure you choose for your first investment loan influences how quickly you can acquire a second or third property. A loan structured with appropriate deposit size, interest-only repayments, and variable rate features preserves both serviceability and equity.

Borrowers who repay principal voluntarily on an investment loan reduce their deductible debt and lock capital into a single asset. That capital could otherwise be used as a deposit for a second property. Where portfolio growth is the objective, interest-only repayments on investment loans and principal-and-interest repayments on the owner-occupied home typically provide the most efficient structure.

Lenders assess each investment loan application on a standalone basis, but they also consider the borrower's total exposure to property, total debt, and overall serviceability. A borrower with multiple investment loans and high total debt may reach a point where additional lending is declined regardless of the individual property's rental yield or capital growth potential. Structuring each loan to preserve serviceability, particularly by maintaining offset balances and managing LVR, delays that constraint.

Call one of our team or book an appointment at a time that works for you. We assess your borrowing capacity, compare loan products from across the Australian lending panel, and structure each facility to support your broader investment objectives.

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