Common Mistakes in Investment Loan Optimisation

Borrowing Against the Wrong Security

Attaching an investment loan to the wrong property undermines both your tax position and your ability to refinance later. The deductibility of interest depends on what the borrowed funds are used for, not which property secures the loan. If you borrow against your investment property to renovate your home, that interest is not claimable. If you borrow against your home to purchase an investment property, the interest is fully deductible.

Consider an investor who owns an apartment in Burwood outright and wants to purchase a second property in Brunswick. She secures the loan against the Burwood apartment. Five years later, she wants to sell the Brunswick property and refinance the Burwood apartment to access equity for a third investment. Because the loan is secured against Burwood but was used to purchase Brunswick, lenders treat it as cross-collateralised debt. Refinancing becomes complicated, and she loses flexibility when it comes time to divest or restructure.

The alternative is to secure the Brunswick loan against the Brunswick property itself, using the equity in Burwood as a deposit via a separate line of credit or guarantor arrangement. This keeps each loan tied to its corresponding asset, preserves deductibility, and allows either property to be sold or refinanced independently.

Mixing Investment and Private Debt on a Single Facility

Combining loans for different purposes within the same account creates confusion at tax time and limits your ability to claim the full deduction. Once funds are mixed, the ATO requires apportionment based on the purpose of each draw, and lenders do not track this for you.

In our experience, this happens most often when investors use an offset account or redraw facility attached to an investment loan to fund private expenses or home improvements. The moment non-deductible funds are withdrawn, the interest calculation becomes blurred. You will need to reconstruct each transaction to determine how much interest relates to the investment component, and most investors do not maintain the necessary records.

The solution is to split loans by purpose from the outset. Use one facility for the investment property, another for your home, and a separate line of credit for private expenses if needed. This separation makes tax reporting straightforward and ensures you claim every dollar of deductible interest without the need for complex apportionment.

Overlooking Interest Only Periods for Cash Flow Management

Principal and interest repayments reduce debt, but they also reduce the deductible portion of your loan over time. For investors holding property in growth areas like Burwood, where median values have risen consistently over the past decade, preserving deductible debt and redirecting surplus cash flow toward the non-deductible home loan or additional deposits can deliver a greater long-term benefit.

Interest only repayments on an investment loan allow you to claim the maximum deduction each year while keeping monthly outgoings lower. This frees up cash flow to pay down your owner-occupied mortgage, which carries no tax benefit. Once your home loan is cleared or reduced substantially, you can switch the investment loan to principal and interest or use the additional cash flow to fund further investments.

Most lenders offer interest only periods of up to five years on investment loans, with the option to extend or revert depending on your circumstances. The key is to have a defined plan for the cash flow you preserve, rather than allowing it to drift into general spending. Investors who treat interest only as a strategy rather than a convenience tend to build equity faster across their overall portfolio.

Failing to Account for Negative Gearing Changes After July 2027

The Treasury Laws Amendment (Tax Reform No. 1) Act 2026 fundamentally alters the tax treatment of residential investment properties acquired on or after 7:30pm AEST on 12 May 2026. From 1 July 2027, net rental losses on these properties can only be offset against other residential rental income or carried forward. They cannot be used to reduce salary or wage income.

Investors who purchase established apartments or houses in Burwood after that date will need to structure their portfolios differently. If you rely on negative gearing to reduce your taxable income each year, you will either need to target properties that generate positive cash flow from the outset or acquire eligible new builds, which remain exempt from the quarantine rules.

Eligible new builds include dwellings constructed on previously vacant land and developments that increase the total number of dwellings on a site. Knock-down rebuilds that do not add dwellings, and substantial renovations, do not qualify. A new build occupied for more than 12 months before being sold to a subsequent investor also loses the exemption for that purchaser.

Properties held at 7:30pm AEST on 12 May 2026, including those under contract at that time, are grandfathered and continue under existing negative gearing rules until sold. If you are planning to expand your portfolio, understanding which assets retain full deductibility and which are subject to quarantine is central to structuring your borrowing and acquisition sequence.

Ignoring the Serviceability Impact of Debt-to-Income Caps

APRA introduced debt-to-income caps on 1 February 2026, limiting the proportion of new investor loans that can be written at six times income or above to 20 per cent of each lender's investor portfolio. This does not prohibit high-DTI lending outright, but it does mean lenders are more selective about which applications they approve above the threshold.

If your total debt across all properties is already sitting at or above six times your gross annual income, some lenders will decline your application regardless of your deposit size or rental yield. Others will approve it but apply higher interest rates or stricter conditions. This makes it harder to expand your portfolio unless you increase your income, reduce debt, or structure loans across multiple entities or guarantors.

Burwood investors with strong rental income from existing properties can improve their serviceability by ensuring rental income is fully recognised in the assessment. Most lenders apply a haircut of 20 to 30 per cent to account for vacancy and maintenance, but some will accept 80 per cent or more if the property has a long lease in place or is in a low-vacancy precinct. Providing a rental appraisal from a local agent and demonstrating consistent occupancy can shift the assessment in your favour.

Another option is to refinance existing loans to lower variable rates or extend interest only periods, which reduces the assessed repayment amount and frees up serviceability for new borrowing. This is particularly relevant for investors who took out loans in the past two years at higher rates and have not yet reviewed their cost structure.

Using Equity Without a Clear Replenishment Plan

Accessing equity to fund additional purchases is a common strategy, but without a plan to rebuild that buffer, you leave yourself exposed if values correct or if you need to refinance under tighter lending conditions. Equity is not income, and each time you draw it down, your loan-to-value ratio increases.

Lenders assess equity positions at the time of each application, and if your LVR has crept above 80 per cent due to market movement or additional draws, you may face Lenders Mortgage Insurance on the next transaction even if you avoided it previously. In areas like Burwood, where apartment values can be sensitive to oversupply or changes in local infrastructure, relying on continued growth to maintain your equity buffer is not a reliable assumption.

The approach that works is to set a target LVR for each property and to rebuild equity through either principal repayments or capital growth before drawing again. If you release equity to fund a deposit on a second property, direct future cash flow toward reducing the debt on one of the two assets rather than drawing further. This creates a cycle of growth and consolidation rather than a steady climb in leverage with no capacity to absorb downturns.

Locking in Fixed Rates Without Considering Break Costs

Fixed rate loans provide certainty, but they come with limited flexibility. If you need to sell, refinance, or pay down a fixed loan before the term expires, most lenders will charge break costs based on the difference between your locked rate and the current wholesale cost of funds. In a falling rate environment, these costs can reach tens of thousands of dollars.

Investors in Burwood who fixed during the rate rises in previous years are now facing decisions about whether to hold those loans to maturity or absorb the cost of breaking early to access lower variable rates. The calculation depends on the remaining term, the size of the loan, and how much rates have moved since the fix was locked in.

One way to reduce this risk is to split your borrowing between fixed and variable portions. A common structure is 50 per cent fixed for rate protection and 50 per cent variable for flexibility. This allows you to make extra repayments or refinance part of the loan without triggering break costs on the entire balance. If your situation changes, you retain options without being penalised for the full loan amount.

Before committing to any fixed term, confirm the lender's break cost formula and ask for an estimate based on different rate scenarios. Some lenders cap break costs or waive them in specific circumstances, and these terms should be factored into your decision alongside the headline rate.

Underestimating Holding Costs When Rental Income Drops

Burwood sits close to Deakin University's Melbourne Burwood Campus, and much of the rental demand in the area comes from students and university staff. When enrolments shift or international student numbers fluctuate, vacancy rates can rise quickly. Investors who assume continuous occupancy without building a buffer for periods without rental income often find themselves unable to meet loan repayments and holding costs during these gaps.

Holding costs include loan interest, body corporate fees, council rates, insurance, property management fees, and utilities. For a two-bedroom apartment in Burwood, these can easily exceed two thousand dollars per month. If the property sits vacant for eight weeks, you need at least four thousand dollars in accessible funds to cover the shortfall.

Structuring your loan with an offset account rather than a redraw facility gives you immediate access to surplus funds without needing lender approval. Funds in offset reduce the interest charged each day but remain available for withdrawal at any time. This is particularly useful during vacancy periods or when unexpected maintenance costs arise. Redraw facilities, by contrast, often require several days' notice and may be restricted if your loan is in arrears or if the lender has changed its credit policy.

Another option is to negotiate a repayment buffer with your lender at the time of application. Some lenders allow you to make advance payments that sit in a separate account and are drawn automatically if you miss a scheduled repayment. This avoids default notifications and protects your credit file during short-term disruptions to rental income.

Frequently Asked Questions