The Easiest Way to Finance a Duplex Investment

A duplex purchase is treated differently by most lenders.

Where a standard investment loan might allow 90 per cent borrowing with lenders mortgage insurance, a duplex on one title typically caps at 80 per cent, and in some cases 70 per cent depending on whether the properties are tenanted separately or treated as a single dwelling. The distinction matters because it changes how much deposit you need and whether LMI is required at all.

How Lenders Assess a Duplex on One Title

Most ADIs classify a duplex on a single title as a non-standard security. Under APS 112, the loan attracts a higher risk weight than a conventional dwelling, which flows through to serviceability assessment and the maximum loan to value ratio the lender will offer. Some lenders will lend to 80 per cent where both units are independently tenanted and the property is in a metropolitan area with strong rental demand. Others restrict lending to 70 per cent regardless of tenancy arrangement. The difference in policy can mean an additional deposit requirement of tens of thousands of dollars on the same property.

Consider an investor looking at a dual-occupancy property in Armadale priced within the suburb's median range for attached dwellings. One lender quotes 80 per cent with dual rental income recognised in full. Another restricts the loan to 70 per cent and applies a 20 per cent vacancy factor to the second unit's rental income, even where both tenancies are in place at settlement. The second structure requires a larger deposit and reduces borrowing capacity by limiting how much rental income offsets the loan repayment in the serviceability calculation. That outcome is determined by lender policy, not the quality of the asset or the investor's financial position.

Interest Only Repayments and Cash Flow Planning

Interest only loans remain available for investment property purchases, including duplexes. The interest only period is typically five years, after which the loan reverts to principal and interest unless refinanced. Interest only repayments reduce the monthly outgoing during the initial hold period, which can be useful where the investor's strategy depends on reinvesting surplus cash flow or maintaining liquidity for further purchases.

Where both units of the duplex are tenanted, rental income from each tenancy is assessed separately. Lenders apply a vacancy rate, commonly 5 per cent, and some also apply a management fee assumption even where the investor intends to self-manage. The net rental income is then used to offset the loan repayment in the debt serviceability calculation. On an interest only loan, the lower repayment amount leaves more rental income available to offset other debts, which can increase overall borrowing capacity when assessed against the 3.0 percentage point buffer and the DTI lending limit introduced in February this year.

Variable Rate or Fixed Rate for a Duplex Investment

Most duplex investment loans are written on a variable rate. Fixed rates are available but tend to be priced higher for investment lending than for owner-occupied borrowing, and the fixed rate period usually caps at five years. Where an investor expects to refinance, sell or access equity within a few years, a variable rate avoids break costs and offers access to offset accounts, which most fixed rate products do not permit.

A split rate structure, part fixed and part variable, can be used where the investor wants rate certainty on a portion of the debt while retaining flexibility on the rest. The fixed portion provides a known repayment for budgeting, and the variable portion allows extra repayments and redraw without restriction. That structure is more common among investors holding multiple properties where cash flow predictability matters, but it adds complexity to the loan and may not suit someone acquiring their first investment.

Rental Income, Vacancy Rates and the Armadale Market

Armadale sits within the City of Stonnington and has historically shown low rental vacancy. Proximity to the Glen Iris border, Kooyong station and High Street retail precinct supports tenant demand for both larger family homes and smaller attached dwellings. A duplex in Armadale typically appeals to professional couples or small families who want access to local schools and public transport without the price point of a detached house in the same catchment.

Lenders assess rental income based on a valuation or a rental assessment provided at the time of application. Where the duplex is already tenanted, the lender will request copies of the lease agreements. Where it is vacant, a licensed valuer will provide a rental range, and the lender will typically use the lower end of that range for serviceability. The difference between assessed rent and actual rent can affect whether the loan is approved, particularly where the investor is also servicing other debt or is close to the DTI limit.

Negative Gearing and the Legislative Changes from 2027

Under current legislation, losses from an investment property, including interest, rates, insurance and other holding costs, are deductible against all assessable income. For a duplex acquired and settled after 7:30pm AEST on 12 May 2026, those losses can only be offset against other residential property income from the 2027-28 income year onward unless the duplex qualifies as an eligible new build. A knock-down rebuild that replaces one dwelling with two on the same title would qualify. A purchase of an existing duplex would not.

For investors acquiring an established duplex in Armadale during the current financial year, losses can be deducted against salary or business income until 30 June 2027 only. From 1 July 2027, excess losses must be quarantined and carried forward to offset future rental income or capital gains from residential property. That change affects cash flow, particularly in the first few years of ownership where interest costs are high and rental income has not yet increased with inflation. Tax planning before exchange of contracts is now part of the duplex purchase decision, not an afterthought.

How Equity in Your Home Can Fund the Duplex Deposit

Most duplex investors use equity release from an existing property rather than cash savings. Where the investor's home has sufficient equity and is not already mortgaged to 80 per cent, the lender can provide a top-up loan secured against the home to fund the deposit and settlement costs on the duplex. The duplex itself is then purchased with a separate investment loan at up to 80 per cent, depending on lender policy.

This structure keeps the home loan and investment loan separate for tax and reporting purposes. Interest on the portion of borrowing used to acquire the investment is deductible. Interest on borrowing used to acquire or renovate the family home is not. Mixing the two on a single loan account makes tax reporting more difficult and can lead to errors in the investor's annual return. Establishing the security and purpose of each loan correctly at the outset avoids those issues and provides clarity if the investor later wants to refinance the investment loan or sell one property while retaining the other.

Borrowing Capacity and the Debt to Income Limit

From 1 February this year, ADIs are required to limit new investor lending above a DTI ratio of six times to no more than 20 per cent of their quarterly investor loan flow. The ratio is calculated using the borrower's total debt, including the proposed new loan, divided by gross annual income before tax. For a duplex purchase, both the new investment loan and any equity release or top-up borrowing used to fund the deposit are included in total debt.

Where the investor's DTI exceeds six, the loan may still be approved, but it will count against the lender's quarterly allocation for high DTI lending. Some lenders manage this by applying stricter serviceability overlays or requiring a larger deposit to bring the DTI below the threshold. Others may decline the application or offer a lower loan amount. The impact is greatest for borrowers with high income but also high existing debt, such as investors who already own multiple properties or have recently refinanced to access equity. Running a borrowing capacity assessment before making an offer allows the investor to know whether the duplex purchase is within reach or whether debt reduction is needed first.

Settlement Costs and Stamp Duty on Investment Property

Stamp duty on investment property in Victoria is calculated on the dutiable value, which is usually the purchase price. No concessions or exemptions apply to investment purchases. For a duplex within Armadale's attached dwelling price range, stamp duty will typically sit between five and six figures depending on final sale price. That cost is payable at settlement and cannot be added to the loan amount under standard lending policy.

Other settlement costs include legal fees, building and pest inspection, loan establishment or application fees, valuation fee if charged separately, and title registration. Where LMI applies, the premium is also due at settlement and can be capitalised into the loan amount. The total upfront cost, excluding the deposit, usually sits between 4 and 6 per cent of the purchase price for an established duplex. That figure should be confirmed with your conveyancer and broker before exchange, as it affects how much equity or cash is required to complete the purchase.

When to Speak to a Broker About a Duplex Investment Loan

Duplex lending policy varies widely across ADIs and non-bank lenders. Some lenders will not accept a duplex on one title under any circumstances. Others will lend but apply restrictions on the rental income they recognise or the LVR they allow. A broker with access to investment loan options from banks and lenders across Australia can identify which lenders suit the property type and the investor's financial position, then structure the application to meet the policy requirements of that lender.

That structure includes how the deposit is sourced, whether the loan is interest only or principal and interest, whether an offset account is available, and how rental income is presented in the serviceability assessment. Getting those details right before lodgement reduces the chance of a declined application or a conditional approval that cannot be satisfied. For Armadale investors looking at dual-occupancy property as a long-term hold or a stepping stone to a larger portfolio, the loan structure set up at purchase will either support or constrain what comes next.

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