Everything You Need to Know About Investment Loans

An investment loan lets you purchase a rental property while using the income from tenants to help service the debt.

The structure differs from an owner-occupied mortgage because lenders assess serviceability based on rental income minus vacancy and property expenses, and because taxation of the interest changes depending on when you buy and what type of dwelling you choose. In South Australia, where median property prices remain lower than Sydney or Melbourne, a single rental property can still be within reach for buyers who understand how lenders calculate borrowing capacity and structure the application to align with their income.

How Lenders Assess Rental Income for Investment Loans

Lenders apply a shading factor to rental income, typically accepting 70 to 80 per cent of the advertised rent when calculating serviceability. A property renting for $500 per week generates $26,000 annually, but the lender may only use $18,200 to $20,800 in its assessment. This accounts for vacancy periods, property management fees, and rates.

Consider a buyer purchasing a unit in the Adelaide CBD with rental income of $450 per week. If the lender applies a 75 per cent shading factor, the recognised income is $17,550 per year. The buyer also needs to service the loan using their salary, as rental income alone rarely covers the full repayment at today's rates. Lenders add a serviceability buffer of three percentage points above the product rate when stress-testing repayments, so a loan advertised at 6.2 per cent variable is assessed at 9.2 per cent.

Property management fees in South Australia typically range from 6 to 8 per cent of gross rent. Body corporate fees, council rates, and landlord insurance reduce net income further, and these expenses are factored into your post-settlement cash flow rather than the lender's upfront serviceability calculation.

Interest Only Investment Loans and Cash Flow

Interest only repayments reduce the monthly obligation compared to principal and interest, freeing up cash flow during the initial years of ownership. Most lenders offer interest only periods of one to five years on investment loans, after which the loan reverts to principal and interest unless you negotiate an extension or refinance.

A $400,000 loan at 6.3 per cent on interest only costs approximately $2,100 per month. The same loan on principal and interest over 30 years costs around $2,475 per month. The $375 difference can be redirected toward holding costs, additional investments, or offset against other debt. However, interest only loans do not reduce the principal balance, so you finish the interest only period owing the same amount you borrowed.

Interest only is commonly used by investors who prioritise cash flow, plan to sell within a defined period, or intend to make lump sum reductions from other sources. It is not suited to buyers who want to build equity through regular repayments or who may struggle to afford the higher repayment when the loan reverts.

Fixed Rate vs Variable Rate for Investment Property Finance

A fixed rate locks in your repayment for one to five years, protecting you from rate rises but preventing you from benefiting if rates fall. A variable rate moves with the lender's pricing cycle, and usually offers access to offset accounts and unlimited additional repayments without penalty.

In our experience, investors who plan to hold long-term and want repayment certainty during the early years often split their loan, fixing a portion and leaving the remainder on variable. This allows partial protection from rate increases while retaining flexibility to make extra payments or redraw if needed. Fixed rates do not typically allow offset accounts, so any surplus cash sits in a separate savings account earning taxable interest rather than reducing the loan balance tax-free.

If you fix and then need to refinance your investment loan before the fixed term ends, break costs may apply. These are calculated based on the difference between your fixed rate and the lender's current wholesale funding cost for the remaining period. Break costs are rarely disclosed upfront and can run into thousands of dollars if rates have fallen significantly since you locked in.

Loan to Value Ratio and Lenders Mortgage Insurance

Lenders Mortgage Insurance is charged when your deposit is less than 20 per cent of the property value. On investment lending, some lenders cap LVR at 90 per cent, and others will only lend to 95 per cent if you also hold owner-occupied debt with the same institution.

LMI on a $450,000 loan with a 10 per cent deposit can range from $12,000 to $18,000 depending on the lender and your employment type. The premium is typically capitalised into the loan amount rather than paid upfront, increasing your total debt and ongoing repayments. Certain professions qualify for LMI waivers at higher LVRs, reducing or eliminating the premium even with a deposit below 20 per cent.

If you already own property, you may be able to use equity release as your deposit rather than saving cash. A property valued at $600,000 with a $300,000 mortgage has $300,000 in equity, and lenders typically allow you to borrow up to 80 per cent of that equity without LMI. This approach is common among buyers expanding their property portfolio using existing holdings as leverage.

How the July 2027 Tax Changes Affect Investment Loan Strategy

From 1 July 2027, rental losses on established residential properties purchased after 12 May 2026 can only be offset against other residential rental income or carried forward. They cannot be deducted against salary or wages.

This quarantining does not apply to eligible new builds, defined as dwellings constructed on previously vacant land or where the build increases the number of dwellings on the site. A knock-down rebuild that replaces one house with one house does not qualify. A development that replaces one house with two townhouses does.

For South Australian buyers, this shifts the focus toward new or near-new stock in growth corridors where land supply supports construction. Suburbs such as Mount Barker, Munno Para West, and Angle Vale have seen significant residential development, and newly completed dwellings in these areas retain negative gearing access for the first purchaser. If that purchaser later sells to another investor after occupying or renting the property for more than 12 months, the second investor loses access to negative gearing.

Properties purchased before 12 May 2026, or under contract at 7:30pm on that date, continue under the old rules indefinitely. Buyers who settled in early 2026 retain full negative gearing until they sell, regardless of how long they hold.

Investment Loan Application and Supporting Documents

Lenders require proof of income, asset statements, identification, and a signed contract of sale or property valuation. For investors, the rental appraisal or current lease is also assessed. Self-employed applicants provide tax returns and financial statements, usually covering the most recent two years.

If you are purchasing in a regional area or in a postcode flagged by the lender's policy team, additional serviceability overlays may apply. Some lenders reduce the rental income shading further or require a larger deposit in areas with vacancy rates above a certain threshold. Adelaide's inner suburbs generally do not attract these overlays, but towns in regional South Australia occasionally do.

Debt-to-income caps introduced in February 2026 limit the portion of new lending a bank can write at six times income or more. In practice, this affects higher-LVR borrowers with multiple liabilities or those purchasing at the top of their serviceability range. It does not prohibit high-DTI lending outright, but lenders ration approvals and may require larger deposits or co-borrowers to bring the ratio below the threshold.

Why Offset Accounts Matter for Investment Loans on Variable Rates

An offset account is a transaction account linked to your loan. Every dollar in the offset reduces the balance on which interest is calculated, lowering your repayment or the interest component of it without formally paying down the loan.

For investment lending, keeping the loan balance high and the deductible interest maximised is often preferable to reducing principal. An offset lets you park surplus cash and reduce interest expense without losing the ability to redraw or repurpose those funds. Interest saved through an offset is not counted as income, so it delivers a tax-free benefit equivalent to earning interest at your marginal rate plus Medicare levy.

Not all lenders offer full 100 per cent offset, and some link only partial offset or cap the balance that offsets. Confirming this feature during the investment loan application avoids surprises after settlement.

What Happens When You Want to Refinance an Investment Loan

Refinancing an investment loan follows the same serviceability assessment as a new application, including shading of rental income and stress testing at the buffered rate. If your property has increased in value or you have paid down principal, your LVR improves and you may qualify for a lower rate or access equity for further purchases.

We regularly see investors refinance to consolidate debt, switch from interest only to principal and interest as they near retirement, or move to a lender offering better offset features. Discharge fees, valuation costs, and any remaining fixed-rate break costs should be weighed against the ongoing saving. A rate reduction of 0.3 per cent on a $400,000 loan saves approximately $1,200 per year, so if refinancing costs $1,500, the payback period is just over 12 months.

If you are refinancing to release equity, lenders reassess your income and liabilities as at the date of the new application. A second investment property purchased using released equity is subject to the same tax rules as any other purchase after 12 May 2026, meaning negative gearing access depends on whether it is an eligible new build.

Interest Rate Discounts and How to Access Them

Published investment loan rates are starting points. Most lenders offer rate discounts based on loan size, LVR, and whether you hold other products with the institution. A package that includes transaction accounts, offset, and insurance can reduce the rate by 0.3 to 0.7 percentage points.

Discount structures are not always transparent, and the same lender may offer different discounts to different borrowers based on perceived risk or broker negotiation. Asking your broker to request a rate match or discount review before settlement can result in a lower margin without changing lender. Once the loan settles, your ability to negotiate diminishes unless you threaten to refinance.

Lenders also reprice their back book periodically, and investment loans on variable rates may be increased out of cycle if the lender is managing portfolio risk or capital requirements. Monitoring your rate every six months and comparing it to current offers keeps you informed.

Call one of our team or book an appointment at a time that works for you to discuss how investment loan options align with your income, deposit, and property goals across South Australia.

Frequently Asked Questions