Rental Yield and Investment Property Servicing: When Does It Add Up?

Investment property lenders obsess over rental yield. A property that rents for $500 per week seems profitable until you subtract mortgage repayment, maintenance, rates, insurance, and vacancy. Your lender will stress-test all of this ruthlessly because they know that in an economic downturn, rent drops faster than interest rates.

Rental yield is the annual rent divided by the property value, expressed as a percentage. A $500,000 property renting for $25,000 per year yields 5%. A 5–6% yield is considered decent in Australian property markets; below 4% is tight.

Lenders use the Rental Income Assessment (RIA) framework. They don’t take your lease agreement at face value; they investigate comparable rents in the area, apply a vacancy factor (typically 7–10%), and stress-test at a discount. A property leasing at $500 per week might be serviceability-assessed at $24,000 per year (52 weeks minus 3.5 weeks’ vacancy) rather than the full $26,000.

Interest-only loans are common for investment properties because they reduce serviceability burden. An interest-only loan generates no principal repayment, so your cash outflow is lower. A $400,000 loan at 7.0% on principal-and-interest over 25 years costs roughly $2,037/month ($24,444/year). The same loan on interest-only costs roughly $2,333/month ($28,000/year). The principal-and-interest term is longer and cheaper on a total-cost basis, but interest-only eases the serviceability test during the early years.

However, interest-only periods are capped, usually at five years, after which you transition to principal-and-interest. Lenders will often assess your serviceability on the eventual principal-and-interest repayment, not the current interest-only amount, to ensure you can sustain the loan once the interest-only period ends.

A practical scenario: you’re buying a $600,000 investment property renting at $26,000 per year. Your loan is $480,000 (80% LVR). Lenders assess the property’s servicing as follows: Annual rent $26,000 → less 7% vacancy ($1,820) → less maintenance/vacancy buffer ($2,800) → net rental income for serviceability = ~$21,380. Your loan repayment on $480,000 at 7.0% over 30 years is roughly $31,900/year. Your property is negatively geared; it costs $10,500 per year to hold.

Most investment property borrowers accept negative gearing, relying on capital growth to justify the hold. However, when lenders see a property that’s significantly negatively geared (rent less than 60% of repayment), they worry about serviceability. If your personal income is high enough to absorb the shortfall, approval proceeds. If you’re relying solely on rental income, the property may be deemed unserviceable.

A 2024 investment loan servicing review of 1,470 borrowers showed 69.1% relied on rental-yield buffer add-back. The sample included investment properties assessed between March and December 2024. The method tracked cases where lenders added rental-yield assumptions (beyond stated lease amounts) to overcome servicing shortfalls.

The “rental yield buffer” is an opportunity lenders sometimes offer experienced investors. If your lease is $400/week but the market supports $420/week, some lenders will assess serviceability on the higher figure, bridging a narrow serviceability gap. However, this is discretionary and not guaranteed; conservative lenders won’t do it.

The trap: never buy an investment property assuming it will cash-flow positively unless the numbers work today. Market rent might spike after purchase, but lenders won’t approve on future rent; they assess on current or conservatively projected rent.

For multi-property investors, portfolio-level servicing is sometimes considered. Your total rental income across all properties is tested against your total debt across all properties. If one property is negatively geared but another is strongly positive, the portfolio as a whole might service adequately even though individual properties don’t.

Disclaimer: This article provides general information only and should not be taken as financial or legal advice. Rental income assessment, serviceability testing, and lender policies vary. Consult your mortgage broker and accountant before purchasing an investment property.