Your borrowing capacity determines the loan amount a lender will approve, and it depends on income, existing debts, living expenses, and the lender's assessment rate.
Most professionals assume their salary alone dictates what they can borrow. It doesn't. Lenders calculate your capacity by taking your net income after tax, deducting all committed expenses including credit card limits and other loans, then applying a buffer rate that sits above current interest rates to ensure you could still meet repayments if rates rise. The result often surprises people who expected a higher figure.
How Lenders Calculate What You Can Borrow
Lenders assess your capacity by measuring net income against total financial commitments, then testing those repayments at a higher rate than you'll actually pay. Most lenders add a buffer of 2% to 3% above the actual interest rate when running serviceability tests. If the variable rate you're applying for sits at 6.5%, the lender tests your repayment capacity as though the rate were 8.5% or 9.5%. This buffer protects both you and the lender from rate increases during the loan term.
Income types are weighted differently. A base salary from full-time employment receives full weighting. Bonuses, commission, and overtime might be included at 80% if you can show two years of consistent history. Rental income from investment property typically gets factored at 75% to 80% of the gross amount to account for vacancies and maintenance. Self-employed income requires two years of financial statements, and lenders apply their own calculation methods to taxable income, add-backs, and business structure.
Credit Limits Reduce Your Capacity More Than You Think
Lenders treat credit card limits as though they're fully drawn, regardless of what you actually owe. A card with a $20,000 limit costs you roughly $60,000 to $80,000 in borrowing capacity, depending on the lender and your income level. This applies even if you pay the balance in full each month and never carry debt.
Consider a professional earning $120,000 with a $15,000 credit card limit, a $400 monthly car loan, and no other debts. The credit card limit alone might reduce capacity by $65,000. Closing that card or reducing the limit before applying can shift the approval amount significantly. The car loan, with 18 months remaining, reduces capacity by another $30,000 to $40,000. Lenders calculate committed expenses over the full term of each obligation, not just the monthly amount.
Living Expenses and the HEM Benchmark
Lenders use either your declared living expenses or a benchmark figure called the Household Expenditure Measure, whichever is higher. The HEM is calculated based on household size and income level, and it's not negotiable. If you're single and earning $110,000, your HEM might sit around $2,200 per month. If you declare $1,800, the lender will still assess you at $2,200.
Declaring expenses that are significantly lower than HEM won't improve your application. Lenders built this measure to prevent underestimation. What does affect capacity is reducing discretionary spending categories that sit outside HEM, such as private school fees, childcare, or regular loan repayments to family members. These get added on top of the benchmark figure and directly reduce what you can service.
When Rental Income Affects Your Application
If you're applying for an owner occupied home loan and currently renting out a property you own, that rental income usually helps your capacity. If you're buying an investment property and plan to continue renting yourself, your current rent becomes an ongoing expense that reduces capacity. Lenders treat owner-occupied purchases more favourably than investment purchases because the risk profile differs.
For a professional moving from interstate who owns a property they'll rent out while purchasing in a new location, the rental income from the existing property typically covers most or all of that property's loan repayments. However, the lender still includes your new rental expense in the calculation for the property you're buying. The net effect can reduce capacity unless rental income significantly exceeds the old loan repayment.
Working with Multiple Income Streams
Applications involving two incomes, side businesses, or portfolio income require more documentation but often result in higher borrowing capacity if structured correctly. Lenders assess joint applications by combining both applicants' income and liabilities, then running the same serviceability test. Adding a second applicant increases capacity, but it also brings their debts and credit history into the equation.
A professional with a $95,000 salary and a partner earning $70,000 with no debts might expect to borrow more together than separately. That's usually true, but if the second applicant carries a $25,000 personal loan and two credit cards with a combined $30,000 limit, the benefit diminishes. Running a preliminary borrowing capacity assessment before formally applying shows whether combining incomes actually helps or whether clearing debts first makes more sense.
The Gap Between Online Calculators and Lender Outcomes
Online calculators provide estimates, not approvals. They assume clean credit histories, standard employment, and no unusual expenses. They also apply generic assessment rates and don't account for individual lender policies. One lender might treat your bonus income at full value while another discounts it to 50%. One might accept 80% of rental income while another uses 75%.
In our experience, professionals using online calculators often overestimate capacity by $50,000 to $100,000 because the calculators don't capture credit card limits, HECS debt, or the specific assessment rate each lender applies. A formal assessment through a broker includes those details and tests your scenario against multiple lenders to identify which one offers the highest approval amount based on your actual circumstances.
How HECS Debt Is Treated Across Lenders
HECS and HELP debts reduce your borrowing capacity because lenders treat the repayment threshold as a reduction in your net income. The repayment is calculated as a percentage of your salary once you exceed the income threshold, and that percentage increases as your income rises. For a professional earning $130,000 with a $40,000 HECS debt, the annual repayment might be $6,500, which reduces monthly serviceability by around $540.
Some lenders apply this more conservatively than others. A few lenders calculate the repayment as though your income were higher to build in a buffer. Others apply the current threshold amount without adjustment. The debt itself doesn't appear on your credit file, but you're required to disclose it during a home loan application, and lenders verify it with the Australian Taxation Office during assessment.
Call one of our team or book an appointment at a time that works for you to discuss your specific situation and identify which lenders will assess your income and commitments in the way that supports the loan amount you need.
Frequently Asked Questions
How do lenders calculate borrowing capacity?
Lenders calculate borrowing capacity by taking your net income after tax, deducting committed expenses like loans and credit limits, then testing repayments at a rate 2% to 3% higher than current interest rates. Living expenses are assessed using either your declared costs or the Household Expenditure Measure benchmark, whichever is higher.
Why do credit card limits reduce borrowing capacity even if I pay them off each month?
Lenders treat your credit card limit as though it's fully drawn, regardless of your actual balance or payment habits. A $20,000 limit can reduce your borrowing capacity by $60,000 to $80,000 because lenders assume the potential for full utilisation when assessing serviceability.
Does HECS debt affect how much I can borrow for a home loan?
Yes, HECS and HELP debts reduce borrowing capacity because lenders treat the compulsory repayment as a reduction in your net income. The repayment is calculated as a percentage of your salary once you exceed the threshold, and this directly affects monthly serviceability calculations.
How is rental income from an investment property treated in borrowing capacity calculations?
Lenders typically include rental income at 75% to 80% of the gross amount to account for vacancies and maintenance costs. If you're applying for an owner-occupied loan and renting out an existing property, that rental income generally helps your capacity.
Why do online borrowing calculators show a different amount to what lenders approve?
Online calculators provide estimates using generic assumptions and don't account for credit card limits, HECS debt, individual lender policies, or specific assessment rates. They often overestimate capacity by $50,000 to $100,000 compared to formal lender assessments.
