Why Serviceability Assessment Matters for Your Home Loan

What Is a Serviceability Assessment

A serviceability assessment determines the maximum amount a lender will approve you to borrow based on your income, expenses, and financial commitments. Lenders assess your capacity to service a home loan at an interest rate that is at least 3.0 percentage points above the loan product rate. If you apply for a variable rate at 6.2 per cent, the lender will test whether you can afford repayments at 9.2 per cent.

Consider a buyer earning $95,000 annually who applies for an owner occupied home loan with a 10 per cent deposit. The lender calculates monthly income after tax, deducts existing liabilities such as car loans and credit card limits, subtracts an allowance for living expenses based on the Household Expenditure Measure, and then applies the serviceability buffer to the proposed loan amount. If the assessment shows surplus income after these adjustments, the application can proceed. If the residual income falls short, the borrower may need to reduce the loan amount, increase their deposit, or address outstanding debts before reapplying.

This process applies to all regulated residential mortgage products, whether you are purchasing in Wantirna, refinancing an existing loan, or accessing equity for another purpose.

How the 3 Per Cent Buffer Affects Your Borrowing Capacity

The buffer was increased from 2.5 percentage points to 3.0 percentage points in October 2021 and has remained at that level. A higher buffer reduces the loan amount you can service because the lender must be satisfied you can meet repayments at a significantly higher rate than the one you will pay initially.

For a couple applying jointly with a combined income of $140,000, the difference between a 2.5 per cent buffer and a 3.0 per cent buffer can reduce borrowing capacity by tens of thousands of dollars. The reduction becomes more pronounced when other liabilities are present. A $15,000 car loan, a $10,000 credit card limit, and ongoing childcare expenses all reduce the amount available to service a mortgage.

Borrowers in Wantirna typically service both the mortgage and costs associated with proximity to the Eastlink corridor, including private school fees for households near Wantirna College or St John's Primary School, and vehicle expenses for families commuting to Melbourne's CBD or the Monash employment precinct. These commitments form part of the lender's living expense assessment and directly affect borrowing capacity.

Why Lenders Use the Household Expenditure Measure

Lenders calculate your living expenses using the Household Expenditure Measure, a benchmark derived from Australian Bureau of Statistics data that reflects typical spending patterns for households of different sizes and income levels. The measure is updated periodically and includes categories such as food, utilities, transport, education, and recreation.

If your declared expenses fall below the HEM benchmark, most lenders will apply the higher figure. If your actual expenses exceed the benchmark, the lender will use your declared amount and may request supporting documentation such as bank statements covering a three-month period.

In Wantirna, household expenses tend to sit above the baseline HEM figure due to factors including private school fees, childcare costs, and the prevalence of two-vehicle households. A family with two children attending private schools and both parents working may have committed expenses of $6,000 to $7,000 per month before discretionary spending. These figures directly affect the surplus income available to service a home loan.

Debt-to-Income Limits and What They Mean for Borrowers

APRA activated a DTI lending limit on 27 November 2025, effective from 1 February 2026, applying to all ADIs. Each ADI may lend, measured on a quarterly basis, up to 20 per cent of new owner-occupier loans and up to 20 per cent of new investor loans to borrowers with a total DTI ratio of six times or greater. The limit applies to the total debt you hold, including credit cards, personal loans, and the proposed mortgage, divided by your gross annual income.

For a borrower earning $100,000, a DTI ratio of six equates to total debt of $600,000. If you hold a $20,000 car loan and a $30,000 credit card limit, your maximum borrowing capacity under the DTI limit would be $550,000, even if the serviceability buffer suggests you could afford more. The limit applies at the lender level, meaning individual banks and credit unions must manage their lending within the 20 per cent cap. Borrowers with a DTI above six may still secure approval if they fall within that allocation, but the pathway is narrower.

In our experience, Wantirna buyers with established equity from a previous property sale or those with high incomes relative to their debt levels rarely encounter the DTI limit. Borrowers closer to the threshold may benefit from paying down credit card balances or consolidating personal loans before applying for a mortgage.

How Property Type and Loan Structure Affect Serviceability

The property you intend to purchase and the loan structure you select both influence the lender's serviceability calculation. Where there is any doubt about whether a loan is for owner-occupied or investment purposes, APS 112 requires the loan to be treated as an investment loan. Investment loans are assessed at a higher interest rate floor and attract higher risk weightings, reducing your borrowing capacity compared to an owner occupied home loan.

A borrower purchasing a three-bedroom unit in Wantirna as an owner-occupier on a principal and interest loan will typically achieve a higher borrowing capacity than the same borrower purchasing the same property as an investment with interest-only repayments. The difference can exceed $100,000 depending on income and deposit size.

If you are considering a split loan structure with part fixed and part variable, the lender will assess serviceability using the higher of the two rates plus the buffer. For a fixed rate at 5.9 per cent and a variable rate at 6.3 per cent, the assessment rate applied to the variable portion will be 9.3 per cent. Borrowers seeking certainty through a fixed rate should confirm whether the fixed rate offers a lower assessment outcome before locking in the structure.

What Happens If You Do Not Meet Serviceability Requirements

If the lender's serviceability assessment indicates you cannot service the requested loan amount, the application will be declined or the approved amount will be reduced. Lenders may approve a lower loan amount that satisfies the buffer and DTI requirements, requiring you to increase your deposit, select a lower-priced property, or wait until your financial position improves.

Some borrowers reduce their loan application by paying off personal debts or lowering credit card limits before reapplying. A $20,000 credit card limit costs approximately $60,000 in borrowing capacity even if the card carries no balance, because lenders assume the limit could be drawn at any time. Closing unused cards or reducing limits to $5,000 or less can restore significant capacity.

Alternatively, you may choose to apply for refinancing once your income increases or existing liabilities are cleared. Borrowers who receive salary increases, complete car loan repayments, or eliminate ongoing childcare costs may find they meet serviceability criteria 12 to 24 months after an initial decline.

Income Assessment for Self-Employed Borrowers and PAYG Employees

Lenders treat income differently depending on whether you are a PAYG employee or self-employed. PAYG employees typically provide payslips covering the most recent three months and a letter of employment or contract confirming ongoing income. Lenders assess base salary, and may include allowances, overtime, or bonuses if they are regular and verifiable over a 12-month period.

Self-employed borrowers must provide tax returns, usually covering the most recent two financial years, along with a notice of assessment from the ATO. Lenders calculate assessable income based on net profit after business expenses, and may add back depreciation and other non-cash deductions. If your income fluctuates or has declined in the most recent year, the lender may average the two years or apply the lower figure.

Borrowers operating businesses in Wantirna's retail and service sectors, including those with premises along Burwood Highway or Mountain Highway, should ensure their tax returns reflect sustainable income. Lenders will not assess projected income or turnover growth unless it has already been captured in lodged returns.

How We Approach Serviceability for Wantirna Borrowers

We assess your position before approaching lenders. That includes reviewing payslips, tax returns, and statements for all accounts, calculating your likely HEM outcome, applying the serviceability buffer, and identifying any factors that may limit capacity. If your application sits close to the DTI threshold or if you carry liabilities that reduce capacity, we will discuss options such as debt consolidation, selecting a lender with a more favourable serviceability policy, or adjusting the loan amount before formal submission.

Wantirna buyers often ask whether they should apply for pre-approval or wait until they have paid down existing debts. The answer depends on your timeline and the gap between your current capacity and your target loan amount. Pre-approval provides certainty and allows you to search for properties within a confirmed budget, but if your serviceability outcome is borderline, addressing liabilities first may deliver a higher approval and prevent wasted application fees.

If you are considering a purchase in Wantirna or surrounding areas including Boronia, Scoresby, or Bayswater, call one of our team or book an appointment at a time that works for you. We will calculate your borrowing capacity, explain the factors affecting your serviceability assessment, and identify the loan structure that aligns with your circumstances.

Frequently Asked Questions