What is borrowing capacity and how is it calculated?
Borrowing capacity is the maximum amount a lender will approve based on your income, living expenses, existing debts, and a stress-test buffer applied to the loan rate. It varies between lenders — sometimes by $100,000 or more — which is why comparing options matters as much as getting pre-approved by a single bank.
The Fuller Picture
Lenders assess how much you can borrow by looking at your gross income and then subtracting your committed expenses — things like existing loan repayments, credit card limits, HECS debt, and car finance. What is left is your net monthly surplus, and your borrowing capacity is essentially the loan size that keeps your repayments within that surplus. The actual calculation applies a serviceability rate: the current interest rate plus a buffer (currently 3% above the offered rate under APRA guidelines), which means banks are testing whether you could still afford repayments if rates rose substantially.
Living expenses are assessed using whichever is higher: your declared expenses or a benchmark figure called the Household Expenditure Measure (HEM). Many buyers underestimate this step — if a lender uses HEM and it comes in higher than what you declared, your capacity will be lower than expected. Credit card limits also reduce capacity even if you carry no balance, because lenders assume the full limit as a potential commitment. Reducing or cancelling unused cards before applying can noticeably improve your borrowing figure.
APRA requires lenders to add at least 3% to the actual loan rate when stress-testing repayments. If you are applying for a loan at 6.5%, the bank is checking whether you could afford repayments at 9.5%. This buffer was introduced to prevent borrowers from becoming financially stretched if rates rise significantly after settlement, and it has had a real impact on how much buyers can access compared to earlier rate cycles.
What This Means for Your Purchase
Your borrowing capacity sets a ceiling on your buying budget, but it is not always the number you should borrow to. Lenders are assessing maximum exposure; the right borrowing level for your circumstances may be lower, particularly if your income is variable, you are early in a career, or you expect significant life changes like starting a family. Going in at your absolute capacity leaves no financial buffer for rate changes, unexpected repairs, or periods of reduced income.
Because capacity varies between lenders, it is worth testing more than one before concluding what you can afford. A bank that applies stricter expense benchmarks may approve you for $200,000 less than a credit union or second-tier lender using a slightly different methodology — same income, same expenses, meaningfully different result. A mortgage broker who can run your figures across multiple lenders gives you a clearer picture of your actual ceiling, not just the ceiling of one institution's model.
Existing debts have an outsized effect on capacity. A $20,000 car loan does not just reduce your capacity by $20,000 — it reduces capacity by the ongoing monthly repayment commitment, which might represent $80,000 to $100,000 in purchasing power. Paying down or clearing a car loan before applying for a home loan can shift your budget more than an equivalent income increase would. If you have HECS debt, expect it to reduce capacity by approximately $20,000–$40,000 depending on the outstanding balance and repayment threshold.
How This Shows Up in the Illawarra
In the Illawarra, entry-level houses in suburbs like Dapto, Albion Park, and Berkeley typically start around $700,000–$800,000, while coastal and northern suburbs like Woonona, Corrimal, and Bulli regularly exceed $1,100,000. For a buyer on a single income of $90,000, current borrowing capacity is often in the $500,000–$600,000 range depending on debts and expenses — which puts much of the coast out of reach without additional equity, savings, or a second income. Understanding this gap early helps buyers focus on realistic target areas rather than spending time at inspections they cannot convert.
Wollongong has a high concentration of public sector workers, healthcare professionals, and university employees — many carrying HECS debt — alongside tradies whose income includes overtime and self-employment components that lenders treat differently. If your income is irregular, bonus-dependent, or partially self-employed, some lenders will discount that income in their calculations. Getting a broker or mortgage specialist to run your figures using realistic income assumptions — not just your base salary — is particularly important before you start attending auctions in this market.
Frequently Asked Questions
Does my borrowing capacity change if interest rates drop?
Yes. Because banks stress-test at your loan rate plus 3%, a reduction in rates effectively lowers the assessment rate and can increase your capacity. However, changes in the RBA cash rate take time to flow through, and some lenders apply floors below which they will not reduce the assessment rate regardless of market rates.
Can two people on the same income have different borrowing capacities?
Absolutely. Borrowing capacity is affected by more than just income — your existing debts, credit card limits, number of dependants, spending habits, and employment type all factor in. Two people earning $100,000 each can have capacities that differ by $150,000 or more depending on their financial commitments.
I am a first home buyer with no debts — what should my capacity look like?
Without existing debts, your capacity is primarily limited by income and living expenses. A buyer on $85,000 with modest expenses and no existing debts might access $450,000–$550,000. Adding a second income or a guarantor can change this significantly. A mortgage broker can give you a realistic estimate based on your actual figures.
How long before I buy should I check my borrowing capacity?
Ideally 3–6 months before you intend to buy. This gives you time to close unused credit cards, pay down debts, and address anything on your credit file before a formal application. Pre-approval typically lasts 3 months, so timing your formal application to your search timeline matters.
What if my borrowing capacity comes in lower than I need?
Options include saving a larger deposit (which reduces the loan amount needed), clearing existing debts, improving your income, or applying with a co-borrower. Changing lenders is also worth exploring — capacity varies meaningfully between institutions. A buyers agent can also help you identify properties that represent better value within your actual budget rather than chasing a higher capacity figure.
Can a buyers agent help me understand what I can realistically afford in the Illawarra?
A buyers agent cannot give financial advice, but they can help you understand what your borrowing capacity actually buys in the current market — which suburbs are within reach, which property types compete at your price point, and where you are likely to face auction competition at your ceiling. That market translation is often where buyers need the most guidance.
If you would like to understand how your borrowing capacity translates to real buying options in the Illawarra, we are happy to talk through what your budget can realistically achieve. Get in touch with The Shoreline Agency to start the conversation.
