The easiest way to calculate your borrowing capacity

Borrowing capacity is the maximum amount a lender will offer you based on your income, expenses, existing debts, and the loan structure you choose.

Most buyers in Bulimba discover their borrowing capacity is lower than expected, not because their income is insufficient, but because lenders apply serviceability buffers and assess expenses differently than you might at home. A household earning $180,000 combined might assume they can borrow around $900,000, but after lender calculations factor in childcare costs, existing car finance, and a three percent assessment buffer on top of the actual interest rate, the approved amount can drop to $720,000. That gap changes which properties you can target along Oxford Street or near the Bulimba Memorial Park precinct.

How Lenders Calculate What You Can Borrow

Lenders assess your net income after tax, then subtract your declared living expenses, existing debt repayments, and a buffer to account for potential rate rises. The remaining amount is treated as your disposable income, and this figure determines how much you can service in monthly repayments. Each lender uses a different assessment rate, typically two to three percent above the actual home loan interest rate you will pay, to ensure you can still afford repayments if rates increase.

Consider a buyer earning $120,000 annually with no dependents and a $400 monthly car loan. After tax, their monthly income sits around $7,500. The lender deducts $2,200 for living expenses based on the Household Expenditure Measure (HEM), $400 for the car loan, and assesses the proposed loan repayment at an interest rate of 6.5 percent even though the actual variable rate might be 6.2 percent. If the resulting repayment amount leaves sufficient buffer, the application proceeds. If not, the loan amount is reduced until serviceability is met.

The Role of Debt in Reducing Your Capacity

Existing debt has a disproportionate impact on how much you can borrow. A $30,000 personal loan with $700 monthly repayments does not just reduce your borrowing capacity by $30,000. It reduces it by the capitalised value of those repayments over the loan term, which lenders often estimate at around $150,000 to $180,000 in lost borrowing power depending on the rate and term. Credit card limits are treated the same way. A card with a $15,000 limit costs you roughly $75,000 in borrowing capacity even if the balance is zero, because lenders assume you could draw the full limit at any time.

In our experience, buyers preparing to purchase in suburbs like Bulimba often benefit from clearing smaller debts and closing unused credit accounts three to six months before applying for home loan pre-approval. One applicant reduced their credit card limits from a combined $40,000 to $5,000 and paid off a $12,000 personal loan. Their borrowing capacity increased by $220,000, moving them from a budget suited to units near Riding Road to a price range that opened access to character homes closer to Oxford Street.

How Household Expenses Are Assessed

Lenders do not simply accept the expenses you declare on your application. They compare your stated costs against the HEM benchmark, which estimates minimum living expenses based on household size and income. If your declared expenses are lower than HEM, the lender uses HEM instead. If your actual expenses are higher, particularly for childcare, school fees, or medical costs, the lender may use your higher figure, which reduces serviceability.

A household with two young children in Bulimba might spend $3,200 per month on childcare alone. If HEM for that household size is $3,800 total, the lender will use $3,800 unless the applicant provides evidence of the higher childcare cost, in which case the lender applies the actual $3,200 for childcare plus additional HEM categories, pushing the total assessed expense higher. This creates situations where transparency about costs can reduce your borrowing capacity, but understating them risks the application being declined later in the process when bank statements are reviewed.

The Assessment Buffer and Why It Matters

Every lender applies a serviceability buffer to the interest rate when calculating whether you can afford the loan. This buffer ranges from 2.5 to 3 percent above the actual rate, meaning a loan offered at a 6.2 percent variable rate is assessed at 8.7 to 9.2 percent. The buffer exists to protect both you and the lender against rate rises, but it also means your approved borrowing capacity reflects a worst-case scenario rather than current repayment conditions.

Some lenders apply lower buffers or offer slightly more flexible serviceability calculations, particularly for high-income earners or borrowers with substantial equity. This is where working with a broker familiar with home loan options across different lenders becomes relevant. A borrower assessed by one lender at $650,000 capacity might be approved for $710,000 with another, not because the second lender is riskier, but because their buffer and expense assumptions differ.

Income Types and How They Are Treated

Base salary is assessed at 100 percent of its value, but other income types are discounted or require additional documentation. Bonuses are typically assessed at 80 percent if they have been received consistently for two years. Rental income from an investment property is assessed at 80 percent of the gross rent to account for vacancy and maintenance costs. Self-employed income requires two years of tax returns, and lenders average the income across both years, then often apply a further discount if the trend is declining.

A Bulimba resident working in a senior corporate role with a base salary of $140,000 and an annual bonus of $30,000 might assume their income is $170,000 for borrowing purposes. Lenders will assess it as $164,000, which reduces borrowing capacity by around $30,000 compared to the assumed figure. If that same buyer also owns an investment property in Coorparoo generating $2,400 per month in rent, only $1,920 of that rental income is counted, and the lender also deducts the associated mortgage repayment, strata fees, and a buffer for future rate rises on the investment loan.

Loan Structure and Its Impact on Serviceability

The loan structure you choose affects how much you can borrow. A principal and interest loan is assessed at the full repayment amount, but an interest only loan is assessed at the principal and interest repayment even though you will only pay interest for the initial period. This means interest only loans do not improve serviceability in the lender's calculation, though they do reduce your actual repayments in the short term, which can help with cash flow during the interest only period.

Split loans, where part of the balance is fixed and part is variable, are assessed at the blended rate plus the buffer. If you fix 50 percent at 5.9 percent and leave 50 percent variable at 6.2 percent, the lender assesses the repayment at an average rate of 6.05 percent plus their buffer. This structure does not increase borrowing capacity, but it can provide rate certainty on part of the loan while retaining offset flexibility on the variable portion.

Improving Your Capacity Before You Apply

Borrowing capacity is not fixed. You can improve it by increasing income, reducing debt, or adjusting the loan structure and deposit size. Increasing your deposit from 10 percent to 20 percent eliminates Lenders Mortgage Insurance, which does not directly increase borrowing capacity but reduces upfront costs and may open access to lenders with better serviceability policies. Paying down existing debt, even partially, has an immediate effect because lenders recalculate serviceability based on the lower repayment amount.

Closing unused credit facilities is one of the fastest changes you can make. A $20,000 credit card limit you have not used in two years still costs you roughly $100,000 in borrowing capacity. Closing it takes one phone call and is reflected in your credit file within 30 days. Similarly, refinancing a car loan or personal loan to a lower rate or shorter term reduces the monthly repayment, which increases the amount available for your mortgage repayment in the lender's calculation.

Why a Broker Can Increase Your Approved Amount

Different lenders assess income, expenses, and debt in different ways, and the variance in approved borrowing capacity can exceed $100,000 for the same applicant. A broker with access to multiple lenders can identify which one will deliver the highest serviceability outcome based on your specific income and expense profile. This is particularly relevant for self-employed buyers, those with complex income structures, or households with high childcare or education costs that exceed HEM benchmarks.

We regularly see this in Bulimba, where buyers are often dual-income professionals with investment properties or self-employed income from consulting or trades. One lender might assess a $90,000 self-employed income at 100 percent if the trend is stable, while another discounts it by 20 percent if the most recent year is slightly lower than the previous one. That difference alone can shift borrowing capacity by $80,000 to $100,000, which determines whether a buyer can afford a renovated Queenslander near the riverfront or needs to look further inland.

Understanding your borrowing capacity before you start searching gives you clarity on which properties are within reach and where you might need to adjust your deposit, debt, or timeframe. Call one of our team or book an appointment at a time that works for you to assess your capacity across multiple lenders and identify the structure that supports your next purchase.

Frequently Asked Questions