Avoid These 5 Rental Yield Mistakes on Investment Loans

Rental yield is the annual rent a property generates divided by its purchase price, expressed as a percentage.

For investors in St Lucia, where property values are driven by proximity to the University of Queensland and the river precinct, yields tend to sit lower than outer Brisbane suburbs. The difference between a 3.5% gross yield and a 4.2% gross yield on the same property often comes down to how the investment loan is structured, not the property itself.

Using Interest-Only Periods Without a Clear Exit

Interest-only repayments reduce monthly outgoings and improve cash flow, which makes them common on investment loans. The loan amount stays constant during the interest-only period, and repayments switch to principal and interest once that period ends.

Consider a buyer who purchases a two-bedroom unit near the St Lucia Golf Links with a five-year interest-only loan. Monthly repayments during that period are roughly 40% lower than they would be on principal and interest. When the interest-only period expires, the loan reverts to principal and interest repayments over the remaining term, which increases the monthly cost sharply. If rental income has not increased enough to cover the higher repayment, the investor faces negative cash flow or needs to refinance. Lenders assess serviceability at reversion rates, so the switch is not automatic. Some investors find themselves unable to extend the interest-only period because their income or the property's value no longer supports it.

Interest-only works when the investor plans to sell, refinance, or use other income to absorb the reversion. It does not work when treated as a permanent feature without a plan for what happens at year five or year ten.

Ignoring How Loan Features Affect Claimable Expenses

The interest charged on an investment loan is deductible against rental income, provided the loan was used to purchase or hold the investment property. Loan features such as offset accounts, redraw facilities, and split loan structures can alter what portion of the interest remains deductible.

An offset account linked to an investment loan reduces the interest charged, which also reduces the deduction. If an investor uses an offset account for personal savings while holding an investment loan, they lower their interest bill but also lower their tax benefit. A redraw facility allows an investor to withdraw extra repayments made on the loan, but if those withdrawn funds are used for private purposes, the interest on that portion becomes non-deductible. The ATO treats each dollar of borrowing according to its purpose, not the security it is attached to.

For investors holding both owner-occupied and investment debt, the usual approach is to structure the investment loan without an offset and attach any offset account to the non-deductible loan. That keeps the investment loan interest as high as possible within the agreed rate, maximising the deduction, while the offset reduces the non-deductible debt.

Choosing the Wrong Loan-to-Value Ratio for Your Yield Target

Lenders Mortgage Insurance is generally required when the loan amount exceeds 80% of the property's value. The premium is calculated on a sliding scale and can add several thousand dollars to the upfront cost of purchasing an investment property. LMI is a one-time cost, but it is usually capitalised into the loan amount, which increases both the debt and the interest payable over the life of the loan.

St Lucia units, particularly older stock near the university, are often purchased by investors targeting student or professional tenants. A higher LVR allows the investor to retain more cash for other investments or to cover holding costs during vacancy periods. The trade-off is the LMI premium and a higher loan amount, both of which reduce net yield. An investor borrowing 90% instead of 80% might pay an additional premium and carry a larger debt, which can turn a marginally positive yield into a negative one if rents do not meet expectations.

The calculation is whether the rental income, after all holding costs and loan repayments, justifies the higher LVR. In some cases it does, particularly where the investor has other uses for the retained deposit. In others, it does not.

Locking Into a Fixed Rate Without Considering Rental Income Volatility

A fixed interest rate provides certainty over repayments for the fixed period, typically between one and five years. Variable rates move with market conditions, which can increase or decrease repayments during the loan term.

Rental income in St Lucia can fluctuate based on student enrolment cycles, particularly for properties close to the university. A fixed rate locks in the repayment regardless of whether the property is tenanted or vacant. If the investor experiences an extended vacancy or needs to reduce rent to secure a tenant, the fixed repayment does not adjust. Break costs apply if the investor wants to exit the fixed rate early, refinance, or make lump sum repayments beyond any allowed annual limit.

Variable rates allow the investor to make extra repayments, refinance without break costs, and benefit from rate cuts. The downside is exposure to rate rises. Many investors use a split loan structure, fixing a portion of the loan amount for repayment certainty and leaving the remainder on a variable rate for flexibility. That approach is common where rental income is stable but not guaranteed.

Overlooking How DTI Limits Affect Borrowing Capacity for Yield-Focused Purchases

From 1 February 2026, lenders can provide no more than 20% of new investor loans to borrowers with a debt-to-income ratio of six times or greater. The limit applies separately to investment lending and is measured quarterly across each lender's portfolio.

For a St Lucia investor with a taxable income around $100,000, a DTI of six means total debt across all loans cannot exceed $600,000 if they want to remain outside the 20% exception bucket. If that investor already holds an owner-occupied loan and is applying for a second investment loan, the combined debt is measured. Lenders assess serviceability using the 3% buffer on top of the loan rate, which further restricts how much can be borrowed. An investor targeting a higher-yielding property in St Lucia might find their borrowing capacity is capped below the purchase price, even where rental income would comfortably cover repayments.

The DTI limit does not prohibit lending above six times income, but it does mean those loans are rationed. Investors applying at or above that threshold may face longer approval times, requests for additional documentation, or declines from lenders who have already allocated their 20% quota for the quarter. The impact is greater for investors with existing debt or lower incomes relative to the property price.

Rental yield depends on the loan structure as much as the property. The right loan amount, repayment type, rate structure, and LVR can lift yield or suppress it. Call one of our team or book an appointment at a time that works for you.

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