Borrowing capacity determines the maximum loan amount a lender will approve based on your income, expenses, existing debts, and the serviceability buffer they apply to your application.
Lenders use proprietary assessment formulas that weight net income against committed expenses and apply a serviceability buffer typically around 3% above the current variable rate to ensure you can manage repayments if rates rise. Understanding how these calculations work gives you leverage to structure your application strategically rather than accepting the first figure a lender quotes.
How Income Assessment Changes Your Maximum Loan Amount
Lenders assess your net income after tax and deduct any non-discretionary expenses before calculating what portion can service a home loan. Different income types receive different treatment in this calculation.
Salaried income with a consistent payslip history receives full recognition at 100% of stated earnings. Self-employed applicants typically need two years of tax returns, with lenders averaging the declared net profit across both years and applying it at 80% to account for variability. Rental income from investment properties is assessed at 80% of the gross rent to allow for vacancy periods and maintenance costs, then offset against the existing mortgage on that property.
Bonus and commission income requires a minimum 12-month history before most lenders include it in serviceability calculations. A Calamvale applicant earning a base salary of $85,000 plus $15,000 in annual bonuses would see that bonus income assessed at either 80% or 100% depending on the lender's policy and whether the bonus structure is contractual or discretionary. The difference between those two treatments adds roughly $75,000 to maximum borrowing capacity across a 30-year loan term at current variable rates.
The Expense Categories That Reduce Your Borrowing Power
Committed expenses fall into two categories: fixed obligations that appear on your credit file and declared living expenses based on the Household Expenditure Measure (HEM) or your actual spending pattern.
Fixed obligations include existing home loan repayments, personal loan commitments, car lease payments, credit card limits (not balances), and buy-now-pay-later account limits. Lenders assess credit cards at either the full limit or a minimum monthly repayment calculated at 3% of the limit, whichever reduces your serviceability more. A $10,000 credit card limit with a zero balance still reduces your loan amount by approximately $50,000 because the lender assumes you could draw that limit at any time.
Declared living expenses are measured against HEM, a statistical benchmark published quarterly that estimates minimum reasonable living costs based on household size and income level. If your declared expenses fall below HEM for a household of your size, the lender applies the higher HEM figure instead. In practice, this means a couple in Calamvale with two dependents cannot claim living expenses below roughly $2,800 per month regardless of their actual spending habits.
Consider an applicant with $120,000 in combined household income, no dependents, one car loan with $18,000 outstanding at $450 per month, and two credit cards with combined limits of $25,000 and zero balances. Closing both credit cards before lodging the application would increase maximum borrowing capacity by approximately $125,000 because the lender no longer needs to buffer for that potential debt.
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Serviceability Buffers and How They Compress Loan Limits
Serviceability buffers require lenders to assess your ability to repay the loan at an interest rate higher than the actual product rate you will pay.
Most lenders apply a buffer of 3% above the variable rate used in their assessment, meaning even if you are applying for a variable rate currently sitting around 6%, the lender tests your repayment capacity at 9%. This buffer exists to ensure you can still meet repayments if rates rise during the loan term. Some lenders use a floor rate instead, which sets a minimum assessment rate regardless of how low actual rates fall. If the floor rate is 7.5% and the buffer is 3%, your application is assessed at whichever figure is higher.
The buffer has an outsized impact on maximum loan limits because even a small increase in the assessment rate significantly reduces the amount you can borrow. At an assessment rate of 6.5%, a household income of $110,000 with minimal expenses might support a loan amount around $620,000. The same scenario assessed at 9% reduces maximum borrowing to approximately $480,000.
Lenders with lower buffers or lower floor rates can deliver materially higher borrowing capacity for the same applicant. This variance is why comparing lender policies matters as much as comparing advertised interest rates, particularly for applicants near the edge of their serviceability threshold.
Loan to Value Ratio and Deposit Size Impact on Approval
Loan to Value Ratio (LVR) measures the loan amount as a percentage of the property's value and directly influences whether you pay Lenders Mortgage Insurance and how lenders assess risk.
An LVR above 80% typically requires LMI, a one-off premium that protects the lender if you default and the property sells for less than the outstanding loan balance. LMI premiums increase as LVR rises, with a sharp escalation above 90%. For a property valued at $600,000 with a 10% deposit, the LMI premium might sit around $15,000. The same property with a 5% deposit could attract an LMI premium exceeding $25,000.
Some lenders tighten serviceability for loans above 90% LVR by applying stricter expense assessments or higher floor rates. This means two applicants with identical income and expenses might receive different maximum loan amounts depending on their deposit size. If you are applying with a 5% deposit in Calamvale for an owner-occupied purchase, expect serviceability to compress slightly compared to the same application with a 15% deposit, even before accounting for the LMI premium.
Refinancing an existing home loan to access equity for an investment property introduces additional complexity. The lender assesses the new total debt position across both properties and applies rental income from the investment at 80% while testing repayments on both loans at the buffered rate. Applicants often find their total borrowing capacity is lower when consolidating debt across multiple properties than when assessed for a single purchase.
How Split Rate and Offset Structures Change Monthly Serviceability
Structuring your loan as a split between fixed and variable portions or linking an offset account does not change your borrowing capacity in the application phase, but it influences how serviceability is calculated during the loan term.
Lenders assess split loans by applying the serviceability buffer to both the fixed and variable portions separately, then combining the total repayment figure. A split loan with 50% fixed at one rate and 50% variable at another is assessed using the buffer on each portion, meaning the blended assessment rate reflects both products. If the fixed rate portion is locked at a higher rate than the variable portion, your repayment capacity is tested against that higher figure for half the loan balance.
An offset account linked to your variable loan reduces the interest charged on the outstanding balance but does not reduce the repayment figure lenders use for serviceability. Lenders assume a zero balance in the offset account when calculating your ability to service the debt, even if you plan to maintain $50,000 in offset funds. The practical outcome is that offset balances improve cash flow after settlement without influencing the maximum loan amount you can access at application.
This distinction matters for Calamvale applicants weighing whether to park savings in offset or apply them as additional deposit. A larger deposit reduces LVR and may eliminate LMI, directly lowering upfront costs and potentially improving serviceability if the lender tightens assessment above 90% LVR. Holding the same funds in offset preserves liquidity but delivers no serviceability advantage during the application.
Variable Income and Commission-Based Roles in Calamvale
Self-employed applicants and those earning variable income face stricter documentation requirements and different assessment methods that reduce stated income to a conservative figure.
Lenders typically average two years of tax returns for self-employed applicants and apply that average at 80% unless the business structure allows full recognition through a company or trust with consistent profit distribution. An applicant declaring $95,000 net profit in one year and $105,000 in the next would see an average of $100,000 assessed at $80,000 for serviceability purposes. Adding back non-cash deductions like depreciation can increase the assessable income figure, but this requires clear documentation and an accountant's statement confirming the adjustment.
Commission-based employees in industries common around the broader Logan and southern Brisbane corridor such as real estate, finance, or automotive sales often find their commission income discounted or excluded entirely if the employment history is shorter than 12 months. Even with a longer history, lenders may average the past two years and apply only 80% of that average unless the commission structure is contractual and guaranteed.
The difference between 80% and 100% treatment of $30,000 in annual commission income equates to roughly $6,000 in assessable income, which translates to approximately $30,000 in reduced borrowing capacity. Applicants in this position benefit from working with lenders who recognise a higher percentage of variable income or who allow shorter averaging periods for consistent commission earners.
If you are ready to understand where your application sits across multiple lender policies or you need clarity on how recent income changes affect your maximum loan amount, call one of our team or book an appointment at a time that works for you at Your Mortgage Solutions Group.
