Your borrowing capacity determines the maximum loan amount a lender will approve based on your income, expenses, and financial commitments.
Lenders use a standard formula that applies income multipliers and expense benchmarks to determine serviceability, but the output varies significantly between institutions. A buyer earning $95,000 annually with no dependents might qualify for $520,000 with one lender and $580,000 with another, even when submitting identical documentation. The difference lies in how each lender treats discretionary spending, applies buffer rates, and weights existing debts.
The Core Calculation Lenders Use
Lenders assess net income after tax, subtract committed expenses and living costs, then apply a buffer rate to your proposed loan repayment to test whether you can service the debt under stress conditions. The buffer typically sits between 2.5% and 3% above the actual interest rate on your loan.
Consider a buyer in Perth earning $110,000 with a $400 monthly car loan, $8,000 on a credit card with a $12,000 limit, and rent at $2,200 per month. The lender calculates net monthly income, deducts the car loan, applies the Household Expenditure Measure (HEM) or a declared living expense figure (whichever is higher), and includes a notional repayment on the full credit card limit regardless of the actual balance. The remaining surplus is divided by the monthly repayment on a loan at the assessment rate, which produces the maximum borrowing figure. If the buyer reduces the credit card limit to $3,000 and eliminates the car loan before applying, capacity can increase by $80,000 or more depending on the lender's policy.
How Income Type Affects the Outcome
Salaried income is assessed at 100% of gross earnings, while other income types attract varying discounts. Lenders typically apply 80% of overtime or bonus income if it has been received consistently for two years. Self-employed applicants are assessed on net profit after tax as declared in financial statements or tax returns, averaged across the most recent two years.
A buyer working in mining with a base salary of $95,000 and $25,000 in annual overtime will see the overtime component reduced to $20,000 for assessment purposes, bringing the effective income to $115,000 rather than $120,000. If that buyer shifts to a contracted role with a higher base and no overtime component, borrowing capacity typically increases despite similar total earnings, because contracted income is assessed at full value without a discount. This distinction matters when structuring employment arrangements in the months before applying for home loans.
The Expense Side of the Equation
Lenders assess expenses using either your declared living costs or a benchmark figure derived from the HEM, which scales according to household size and income level. If you declare $3,500 in monthly expenses but the HEM benchmark sits at $4,200 for your household profile, the lender applies the higher figure.
Existing debts are treated differently depending on type. Credit cards are assessed on the full limit, not the balance, with most lenders applying a notional repayment of 3% to 3.8% of that limit each month. A $15,000 credit card adds roughly $450 to $570 in monthly commitments even if the balance is zero. Personal loans, car loans, and buy now pay later arrangements are assessed at their actual repayment amounts. Investment property expenses are netted against rental income, with lenders typically applying a discount of 20% to the gross rent to account for vacancy and maintenance.
A buyer holding two credit cards with combined limits of $22,000, a $320 monthly personal loan, and a $2,100 mortgage on an investment property generating $2,400 in monthly rent will see all three components reduce capacity. Closing one credit card and reducing the limit on the other to $5,000 removes approximately $500 in notional monthly commitments, which translates to an additional $120,000 in borrowing power depending on the assessment rate applied.
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Dependents and How They Reduce Capacity
Each dependent increases the living expense benchmark applied by the lender. The HEM adjustment for a household with two children under 16 is significantly higher than for a couple without dependents, even when gross income is identical.
A couple in Canning Vale earning a combined $140,000 with two children will face a HEM benchmark in the range of $4,800 to $5,400 per month depending on the lender's version of the measure. The same couple without dependents might see a benchmark closer to $3,200. That difference of $1,600 per month equates to roughly $350,000 in reduced borrowing capacity at an assessment rate of 6.5%. Childcare costs are sometimes treated as an additional expense on top of the HEM, further compressing capacity during the years when those costs are highest.
Why Two Lenders Produce Different Results
Policy differences between lenders create material variation in outcomes. Some lenders cap living expenses at the HEM and ignore higher declared costs if your spending exceeds the benchmark. Others allow you to declare actual expenses and will assess on that figure if it is below HEM. Assessment rates vary, with some lenders using a floor rate of 6% and others applying 6.8% or higher depending on loan type and loan to value ratio.
Rental income treatment also differs. One lender might apply an 80% shading to gross rent, while another uses 75% or allows you to provide a lease and net the actual income with minimal discount if the property is tenanted. Similarly, overtime and bonus income policies vary. A buyer relying on $18,000 in annual bonuses will find some lenders accept it at 80% with one year's evidence, while others require two years and apply 50% in the first year, full value in the second.
These policy settings compound. A buyer applying to three different lenders with identical financial circumstances might receive capacity estimates of $480,000, $530,000, and $560,000. The highest figure does not necessarily mean the weakest assessment. It reflects the lender's risk appetite, funding cost structure, and target customer profile. Running a comparison across lenders before committing to a property price gives you a defendable upper limit rather than an optimistic assumption.
Improving Capacity Before You Apply
Borrowing capacity responds to deliberate preparation. Reducing or closing credit facilities, clearing short-term debts, and consolidating buy now pay later accounts all create measurable improvement. Each $10,000 in credit limit removed increases capacity by approximately $25,000 to $30,000 depending on the lender's assessment rate.
A buyer in Joondalup earning $102,000 with a $680 monthly car loan and $19,000 in credit card limits might initially calculate capacity at $460,000. Paying out the car loan, reducing the credit limit to $5,000, and ensuring declared expenses sit below the HEM benchmark can lift that figure to $540,000 within three months. The preparation does not change income, but it changes how the lender's formula interprets the application. This approach works when timed correctly. Applying for home loan pre-approval after making these changes allows you to secure a conditional approval at the higher figure before entering the property market.
When to Reassess Your Position
Borrowing capacity is not static. Income changes, rate movements, and policy updates all shift the calculation. A buyer who calculated capacity 12 months ago based on an assessment rate of 6.2% will find the figure has changed if lenders have since moved to 6.8%. Similarly, a pay increase or the removal of a dependent from your household can reopen capacity that was previously constrained.
If you are comparing your current borrowing power against what you qualified for on an earlier application, request a recalculation rather than assuming the previous figure still holds. Lenders adjust their serviceability models regularly, and the inputs you provided last year may no longer reflect your circumstances. Running the numbers again before making an offer protects you from committing to a price you can no longer support, or missing an opportunity because you underestimated your updated capacity.
Call one of our team or book an appointment at a time that works for you to calculate your borrowing capacity using current lender criteria and identify which policy settings will deliver the strongest outcome for your circumstances.
Frequently Asked Questions
What is borrowing capacity?
Borrowing capacity is the maximum loan amount a lender will approve based on your income, expenses, and financial commitments. Lenders apply income multipliers, expense benchmarks, and buffer rates to calculate how much you can borrow while still servicing the debt under stress conditions.
How do credit cards affect borrowing capacity?
Credit cards are assessed on the full limit, not the current balance, with lenders applying a notional repayment of 3% to 3.8% of that limit each month. A $15,000 credit card limit can reduce borrowing capacity by approximately $120,000, even if the balance is zero.
Why do different lenders give different borrowing capacity results?
Lenders use different assessment rates, living expense benchmarks, and income treatment policies. One lender might assess overtime at 80% while another applies 50%, or one may cap expenses at the HEM while another uses declared costs. These policy differences can create variations of $80,000 or more in borrowing capacity.
How can I improve my borrowing capacity before applying?
Reduce or close credit card limits, pay out short-term debts like car loans, and consolidate buy now pay later accounts. Each $10,000 in credit limit removed typically increases capacity by $25,000 to $30,000, depending on the lender's assessment rate.
How does self-employed income affect borrowing capacity?
Self-employed income is assessed on net profit after tax as shown in financial statements or tax returns, averaged across the most recent two years. This often results in lower borrowing capacity compared to salaried income, which is assessed at 100% of gross earnings.
